This is probably the most coherent Fulci film that I've seen. It's a fairly typical zombie movie in terms of plot, but it's just so over the top. For example, where else could you see an underwater battle between a zombie and a shark? The gore quotient is pretty high as well. There's even one scene (the infamous "eye" sequence) that makes a jaded gorehound like myself squirm. Definitely not a movie for everybody, but required viewing for fans of Italian horror.
I've yet to replace my battered old VHS copy of this with the DVD version, but it's on my to-do list. There are several DVDs of the film floating around, but the one that seems to be the nicest is this one from Shriek Show. It definitely blows the other discs away in terms of bonus features.
Even though the movie is called Zombi 2, there technically never really was an original Zombi. The film's title was selected as a way to cash in on the success of George Romero's Dawn of the Dead, which was called Zombi in Italy.