I still play it regularly. I don't have MW2 anymore because it sucks. MW2 might have new features to make it "look" cooler, but the actual gameplay sucked and the spawn system got worse.
COD4 still has the same complaints and flaws, but MW2's are more prevelant, more frequent, and more annoying.
More and more people have been playing it lately, probably for the reasons above. And it's not just noobs, a lot of them are veteran players. About a month ago, it was hard to exit a lobby, and enter another...you were stuck with the same people until that lobby closed. Now, you have a few options as the population is growing again.