Possible Spoilers here chief.
It's nowhere near as good as the first. The premise is that ithe students, instead of killing each other, are sent to kill Nanahara Shuya's terrorist group ( Shuya, the boy who lived from the first movie.)
Also, since they want to focus on team work, each student is paired with someone. If your partner dies, your necklace blows up...
Half the students die in the first 25 minutes.
The movie isn't horrible by any means, it just doesn't live up to the first movie. It's more of a sequel to the events of the first movie then it is a sequel to the original premise (if that makes any sense to you.) The character of Shitaro Kitano ( the daughter of the teacher from the first) is interesting, but besides her and Shuya, there's no character development once so ever (less than the first movie.) In fact, there's only three characters you even need to care about.
As far as buying it, I don't know what to tell you. I bought it, and I don't regret it. I can't gurantee you're going to feel the same way though. It's definately not a shitty movie however. As I said above, a lot of people expected it to be right up there with the first. While it isn't, that doesn't make the movie bad.
Also, the IMDB is usually full of shit
.