A lot of the characters have been eliminated and/or changed a great deal: Pipkin is not an adult rabbit, but a kitten. Blackberry underwent a gender bend, and was turned into a doe. The doe Hyzenthlay is assumed to appear in the series as Primrose (no doubt due to the complexity of the original character's name). El-ahrairah's name is pronounced "Ellerah", as El-ahrairah's a little tricky for the kids to get their tongues around.
While the animation is colourful and crisp, the characters look more like dogs than rabbits: the have long, lean bodies, and long legs. The film's rabbits actually LOOKED like rabbits. The colours in the film were also A LOT LESS saturated than in the series. The scenery was much more realistic in the movie; you could almost smell the grass.
While it is an alright show, don't think that the book is as cutesy if you're unfamiliar with it, as the TV series was obviously aimed at children. The book (and film, from the late 70s) are MUCH darker and violent than the TV series. It's worth a look, but start off with the book and/or movie before watching it.