Fine, I'll say it.
I hate the barbarian.
When this class was introduced in D&D3 it was thoroughly broken; 3.5 didn't fix it; and while Pathfinder balanced things out by powering up other classes (while throwing the barbarian a bit of a nerfy bone in rage powers), it's revealed to be a nonsensical mess of munchkin-ing. It's like the class was designed by a 13-year-old.
Consider what a barbarian is. Historically, "barbarian" is basically a racist term used by ancient Greeks and Romans to describe anyone but themselves. Not that I'm a fan of bigotry, but they got away with it because these were two of the most powerful empires in ancient Europe. They got there by innovating tactics that overwhelmed any tenacity shown by the tribes they conquered. The verdict was out well before the Bronze Age ended: discipline >> dudebro. Any numbers where formations started to matter and civilization won almost every time. Both Greece and Rome were able to expand their borders for as far as they could manage them, and it was only their own decline that allowed eventual defeat. In particular, when the Western Roman Empire fell, its borders were defended by the very same barbarians they were paying to keep out, so it's not like the barbarians ever overcame their weaknesses.
There's a bit of an appeal to the conventional barbarian in D&D/Pathfinder, however, because RPG fights involve numbers among which the barbarian thrives. A little fantasy embellishment can't hurt, either. Small-unit tactics still beat no tactics, but a barbarian's sheer ferocity can often make up the difference. So it's not much of a stretch to design the barbarian class around overpowering, solo melee combat. And I'm fine with that. It's the rest of the class that grinds my gears.
Let's do a rundown of its abilities shall we?
Hit dice - More hit points per die than any other class. I suppose I'm OK with this, given they're supposed to dominate with ferocity and toughness, and every class should have a few unique characteristics.
Skill ranks - I understand one can be skilled without being formally educated, but when it comes to being skilled, nothing beats training. Someone whose main strength is dudebro having more skill ranks than educated clerics, trained fighters or educated and trained paladins? I call bullshit. If anyone should be uneducated and skilled, it's the ranger. The barbarian being only one step behind (and ahead of more rigorously trained classes) just pisses me off. Look, I know you're more likely to use Intelligence as a dump stat but that's your problem.
Fast movement - They get this so they can close quickly on anyone using ranged attacks or magic. I'm sorry, but barbarians were always weak to ranged attacks, and they're hardly unique here (fighters and rogues are unsympathetic). They get close combat; they should eat this weakness like everyone else. The only other class with fast movement is the monk, probably the polar opposite of the barbarian in terms of mentality.
Rage - I'm OK with this as a concept, and at low levels it's quite limited. I have two issues with it, however. One, it provides a Will save bonus. Obviously this is to prevent a barbarian from becoming completely useless as a party ally due to its extreme vulnerability to enchantment/compulsion, which turns the barbarian's power against the party itself. Problem is, the very image of a berserk rage is that it's indiscriminate, so this bonus is a freebie that does the exact opposite of what you'd expect from a rage. Second, even at mid-levels a barbarian can rage whenever it wants for as long as it needs to, unless the opposition drags down the pace of combat to the point that it's not fun anymore. By 10th level or so you might as well assume the rage bonuses are permanent. Which is fine, but then why have the fatigue rule at all?
Uncanny dodge - Why? What does this have to do with barbarism? The only other class that gets uncanny dodge (and, subsequently, improved uncanny dodge) is the rogue. I suppose it reflects their expertise in solo combat (if you're generally on your own you'd better be able to handle surprises and multiple opponents), but these powers take away the rogue's key advantages when they're at a huge disadvantage to begin with. Add this power to the mightiest melee specialist in the game and the rogue might as well not even be in the fight. Monks don't get this power, for fuck's sake.
Trap sense - This makes even less sense. What would barbarians and traps have in common? I'd sooner give rangers this power, as they're typically the woodsmen who regularly deal with snares n' stuff. This is about as munchkin as it gets. Some teenaged brat probably bit it against a simple trap and went crying on the Intarwebs about it.
Damage reduction - Like hit dice, I can accept this as another unique barbarian characteristic if not for everything else. The main limitation of the rage is a penalty to AC, but what does it matter if you're taking less damage and have tons of hit points?
Tireless rage - Meh. Like I said above, by the time a barbarian's 17th level they basically have enough in the tank to rage every round of combat in a day's work, so this eliminates a weakness the barbarian doesn't even have.
So the barbarian has weaknesses that don't really exist, and powers that no one else gets for no reason other than to relieve the player of the unfathomable horror of having to think. Overall, what I see in the above is that some 13-year-old playtested a class specialized to do one thing -- hit very hard -- and got frustrated that it was relatively easy to bring down with smart play. So the little brat whined until he got his way, and the barbarian was loaded with powers that compensate for its conventional weaknesses. Powers that one or no other classes get. That neutralize those other classes' advantages against the barbarian. Let's see how:
Melee - I'd expect it to do well, possibly better than any other class. This is what it was designed to do, of course. I'll let this one slide.
Ranged - Should be a weakness, though nothing's stopping a barbarian from using missile weapons as well. But what it mainly does is use fast movement to close quickly. At higher levels it can use damage reduction to shrug off the attacks. Together, a barbarian could basically just run right through a shower of arrows and then start clubbing archers like baby seals. Which may sound cool, but it sucks for the archer. . . which could very well be a PC ranger.
Combat maneuvers - Probably the barbarian's only real weakness, just because it doesn't automatically get the appropriate feats (perish the thought!). That said, the Strength bonus it gets when raging gives it an advantage, so if a barbarian does get the appropriate feats this isn't a weakness at all. It's certainly not a weakness other classes don't have to deal with.
Magic - Con bonus enhances its Fortitude save. Reflex save could be a weakness, but high hit points (most of any class) allows it to handle damage better than the fighter, which has the same problem. Unlike the fighter, it has the THUPER THPESHUL Will save bonus. Meanwhile, it's also got fast movement to close in a hurry. This is somewhat more of a toss-up than barbarian vs. fighter, especially with a clever use of spells that don't depend on the barbarian failing a save. But one mistake and a sorcerer or wizard has about two rounds to live. Compare that result with how a fighter would deal with a wizard.
Sneak attack - This one really pisses me off. Sneak attack is just about the rogue's only means of dealing significant damage in a fight. Unfortunately for the rogue, barbarian is the only non-rogue class that gets improved uncanny dodge, even though it has no Dexterity-based class abilities whatsoever. And once the rogue's best shot is neutralized, it's toast. The barbarian has more power, more hit points and has damage reduction. It can't even be flanked. What options does the rogue have? Coupled with a high Fort save, fast movement and trap sense, a single barbarian could probably clean out an entire guild of thieves like this.
The counterpoint is that the barbarian class is open to all, so if I think the barbarian's so awesome I should just play one. Unfortunately, it's just not a fun class for someone who likes to think. I concede that the bonuses don't make it invulnerable, but since you have them you might as well rely on them and stick to the barbarian's strengths no matter what the situation calls for. Where this goes from boring to offensive is that these bonuses are also blatantly designed to prevent thoughtful play from working against it -- tactics that work on just about every other class, mind you. Massed ranged attacks? Say hello to damage reduction. Traps? I got trap sense. Magic? I'm tougher than anyone and I get THUPER THPESHUL Will save bonus. You can't even run away from the damned thing (or hold it at bay with obstacles) because it's got fast movement. It's not like I can't bring one down but one way or another I have to contend with powers a berserker shouldn't even have (and no one else gets). I generally don't play monks because they're also a fixed build, but I'm OK with them because they're hardly overpowering. When I make a fighter, or a rogue, or a cleric, or a wizard, I have to think about what I'm doing and the challenge makes the game fun. The barbarian is designed to discourage thought on both sides.