Balance is less of a concern in this game if you look at it this way:
sPvP: Anyone can reroll into one of the more viable classes within literally 10mins and be on equal footing as everyone else; it's only a problem if ONE class is viable, but right not it seems only about 2-3 classes are underpowered. Yes it's definitely no ideal, but it's better than other games (like WoW for example), where you would have to reroll and spend weeks levelling/gearing your character back up.
WvWvW: Classes don't matter much, it's a numbers (and part strategy) game really.
PvE: There is almost no competitive content for PvE, everything is so cooperative; So it doesn't really matter if some classes are overpowered, as long as the underpowered classes are still viable, and at this point in time they all are afaik. Again, yes it's not ideal, but it's much better than having to bring 10 Arcane Mages with legendaries and Rogues to get world first Spine of Deathwing just to have the rest of the world QQ about class stacking.
Seriously, just play and enjoy the game and give Anet time to do the work; the game itself is actually wonderful (and completely different) experience if you can look pass all the vanilla jitters that all the new MMOs will have