I've been playing since Beta 4 (December of 1999). Having played the game for over 8 years, I'd have to argue that the AWP is not overpowered. The AWP costs significantly more than the AK or M4, so it should be better. It fires very slow. It reloads very slow. It slows movement more than any gun when zoomed, and is inaccurate when not zoomed (and the quickshot has been limited in Source when compared to 1.6). It is so loud it can be heard from across the map, making it easy to know when someone is using the gun and where they are in the map. If an AWPer misses a shot, he must dive behind cover quickly, as he leaves himself wide open for return fire.
You want overpowered, look at the AWP in the betas up through version 1.3. It was accurate while moving, it was accurate unzoomed, and you could quickswitch to a pistol and back and fire the AWP faster than if you simply waited to slide the bolt and chamber the next round. Skilled players could aim with a pistol, switch to their AWP and fire instantly, without zooming, and get kills. The gun went through every wall as if they were made of paper. It was an amazingly dominant weapon. And yet, despite the dominance of the AWP, when it came to tournaments, the USA (teams which heavily favored AWP play, like 3D, DoP and rdw) always lost to Europeans (teams which favored rifle play, such as NiP, SK, team9, and many others). The dominance of the AWP was completely overshadowed by tactics and good rifling by skilled players.
That's what it comes down to. CS is meant as a team game. It requires tactics to win. You almost never find coordination in pubs, and when you do, that team will win, regardless of whether the other team is AWPing or not. There's no AWPer in the world who can't be overcome by a team of players working together with an assortment of grenades and a cohesive plan of attack. Maybe the AWP is overpowered in pubs; personally, I don't believe it is, as I'm a fairly decent AWPer, so I can generally hold my own if the other team starts AWPing. Really, it's just that people in pubs focus too much on individual glory and not on unit cohesiveness.
However, it is definitely annoying when servers start players with 16k and every single person on the server is AWPing.