I never saw "Greg the Bunny" during its original run, but after seeing a few clips from it just the other day I got my hands on the pilot episode to check it out.
This show isn't the best sitcom ever or anything, definitely not, but it's hilarious and original and didn't deserve to be canceled when it did, but I guess it was too different for the mainstream audience.
Seth Green is the human star of the show, and he pulls off his role pretty well, but I'm used to seeing him in "Buffy the Vampire Slayer", and he wasn't exactly the stand-up comedian in that show. While he does great in "GtB", the bunny is definitely the best part of the show.
If you like FOX comedies and puppets who say rude things, or the "Smile Time" episode of "ANGEL", you'll probably like this show. Fortunately, it's available on DVD.