I've pretty much stopped playing games altogether, and the ones that I do play are almost all oldies or indie titles. The only series that I still follow closely is Half-Life. I think I know why, too:
Back in the day, a video game was made by two guy's sitting across from each other in a garage. These may not have been the glory days of quality, but they most certainly were the glory days of innovation and creativity. As technology progressed, game development became the concern of a massive number of small companies; the quality here was probably the highest, since there was a greater diversity of opinions, tastes, and concerns during the development process, but the creativity was there, too.
Now, there has been a massive movement towards consolidation and corporatism. There are only a few major game publishers, and they are all concerned primarily with profit (which isn't a fault - they're corporations, they're legally required to ensure the greatest possible returns for their investors). Unfortunately, this makes them extremely conservative. The entertainment industry is one of the world's most volatile, and video games are even more dangerous than most; each major game published is a major risk - often, games don't even make enough money to cover the cost of their development. This means the publishers are going to be careful, and it's in this "being careful" that the problem lies.
To a company like EA or Vivendi, the quality of a game does not matter at all compared to how much money it is going to take in. If you own Monolith, and Monolith pitches you a game that is going to take tens of millions of dollars to produce and which breaks all the rules of videogames, making something completely unique, are you going to fund that game, or are you going to fund a sequel to F.E.A.R., knowing that all the fans of the first ones are going to snap it right up?
Basically, the industry has changed so that it is better for publishers to force out a clone of a successful game than something new and unique or even fun. For this reason, the quality of games overall has been on a steep decline. The last major game I bought was the Orange Box; before that, it was S.T.A.L.K.E.R., and before that, I think it might have been Quake 4. I wasn't even happy with all of those purchases; the Orange Box was great, but Quake 4 was fun but not worth the money, and I found S.T.A.L.K.E.R. boring and frustrating (though kudos to them for trying something relatively fresh). I'm sure I would enjoy the hell out of Bioshock if I tried it, but I just don't think games are worth the investment anymore. Nobody wants to do anything new; I don't think that the same game with different weapons or levels or whatever is worth the $60 or $70 CAD that they cost.