SNL goes through cycles of funny and unfunny and there will always be people saying "it wasn't as good as it was in the early 90s," or something similar, but back then, people were saying the exact same thing. For my money, the worst periods were the mid 80s cast (Anthony Michael Hall, Robert Downey Jr and co) and the mid 90s (after Dana Carvey, Phil Hartman and co. left).
I try to watch the new episodes as often as possible. Tivo has made it easier. So far, I agree with the others, the best episode has been Justin Timberlake. He seemed like he was really willing to go for it in each sketch, and his musical performances were really good also. Halle Berry was just terrible. She's just not right for live TV. And Britney was pitiful. Lip-synched her first number and then tried to sing the second, but she just doesn't have a good voice. Really. She's more pop icon than anything else.
If you're really interested in SNL, I highly, highly recommend
Live From New York. I thought I knew a lot about SNL, but until I read this, I had no clue about how hard these people work each week to make us laugh.