They used to be more gear dependent, but that isn't really the case anymore.
This mostly comes down to four things (that function together).
1. Rage is now more equalized across gear levels.
2. Heroic Strike got put on the GCD, with a CD.
3. Ratings skyrocketed.
4. Armor Penetration
Before now, Warriors have always started off relatively weak early on and soaring to the top of the charts by the end of the expansion. And it isn't hard to see why--with better gear, you'd be hitting more often, and more of those hits would be crits. That led to more initial damage, yes, but no more than any other melee class. The real bonus was the rage that those two stats gave you (plus the additional increase from higher damage output).
All that excess rage just got turned into pure damage, generally, through use of abilities like heroic strike. So, even if the warrior was gcd capped, they'd still be able to spend some turning white hits yellow.
So Warriors needed to be nerfed at the top. The fact that the real problem was the rage system meant that those on the bottom really suffered.
Now, consider all that and remember that nearly all Warrior damage is physical and, as such, subject to armor mitigation. Armor penetration, by nature, got much better the more you had. And when I say much, I mean MUCH. If you took two Warriors, gave them the same stats, but one got 400 ArP, he'd do WAY better. Warriors had way, way more ArP than 400, of course (but that's my point).
Cata addressed that. They normalized Rage to no longer scale with damage, and it's based on your health (or something like that). There aren't any non-GCD abilities to use Rage on, but rather you get HS to use as a GCD if you find yourself with excess rage. And combat ratings are way larger now, so you aren't going to be getting the amounts of hit/crit that would transform Warriors into a powerhouse like they used to.
The final balance was giving them a set amount of built in ArP, and axing the stat from gear.
Really, they aren't any different than other classes now. There might be a SLIGHT difference in the favor of others, but nothing noticeable at all. The normalization helped a lot, and many other classes had their mechanics linked more to combat as well. None as much as Warriors, of course, but most melee classes have some kind of combat-based regen now.
If you are feeling underpowered, it's probably because you are doing something wrong.
But one last note--upgrading your weapons ALWAYS constitutes a huge jump in damage for melee classes. Mages only use their weapons for stats. Stats are just icing on the cake for melee classes. If your weapon has 100 more average damage on it, you are looking at a 33 damage dps increase from auto-attacks alone, before factoring in your haste/crit. Now consider all those abilities you use that scale with weapon damage.
It's no different for DKs, with their strikes, or Hunters with shots, etc.
Anyways, you all are horrible, @#%^ed up people