yeah, I don't think any of the TGIF shows have held up. Full House, Step by Step, Family Matters, and Boy Meets World all suck now but I loved them when I was a little.
I even get really annoyed when I try to watch Fresh Prince nowadays. I can't stand Will's character anymore. Cosby Show is still good in a little spurts here and there (except if it's one of the later seasons with that other little girl). Three's Company has held up well over all these years. Even though they're all basically the same plots and predictable, I chuckle whenever I watch it.
For me, Seinfeld and AD are the only shows that are still as good today as the first time I watched them.