As a player who does not discriminate between classes, I'll point out my problems, which are fortunately few and far in between and not very substantial:
- First of all, the scout scatter gun needs to get a good hit from the nerfstick. I'm not saying it should be as weak as a shotgun, but the amount of damage it deals now coupled with the running speed the scout possesses makes for a very, VERY annoying enemy. Don't get me wrong- I play the scout. I play all classes, depending on what I think my team needs most. I recognize how overpowered the scatter gun is even when I kill people with it. I don't think it's fair- in an optimum range the scout would be just out of melee reach and would be pelting the other person at will while that other will be hard-pressed to simply aim at the scout. Most classes die within two or three direct hits from the scatter gun. I don't think that's fair at all.
- The spy's ability to 'backstab' from the front-side. You know what I mean- when you die while actually watching the spy who stabs you. I'm all for the spy being able to crit-kill while my back is turned and even from my side-and-back, just as long as I am not able to see him, but I am always frustrated when a spy succeeds in stabbing me and getting an easy, free kill which is very hard to prevent (especially if it's a good spy who made a genuine impression) and surely not intended to occur by the developers.
- The pyro, quite honestly, needs even more teeth than he already has. I think the fact that he's increasingly the scariest thing on the map the closer he gets is awesome. Many times, however, I noticed that even before I can get to some players, especially soldiers, or right as I start burning them, I tend to die very quickly. I think the pyro needs either a bit more speed or a bit more firepower. I'd go for a speed upgrade in order to allow pyros to reach their targets and be able to contribute to their team before getting pummelled. I mean, I face it- the pyro is a suicide class. You go in at close range and scare the living crap out of people- but that's the point: disruption. What disruption do you cause when two rockets can kill you on your way to a soldier, or when an explosive kicks you miles away from your target before you could even land a hit on it? It's the way of the game, sure, but I think it'd be a bit better if pyros got a small break.
Everything else about the game, however, is quite impressively well-balanced.