I know a lot of people hated Reanimation (the second CD), but I honestly liked the thing quite a bit. A lot of that was probably due to the fact that I was in high school at the time, but I still really enjoy some of the songs they did on that CD, especially the remix of Crawling.
I don't really think they've gone downhill, but I do think they're a little to "market friendly," i.e. too many remixes. I thought Meteora was a very good quality CD from top to bottom, and had a thicker and better sound than Hybrid Theory. Needless to say, I can't wait for Minutes to Midnight....it's been a long wait.