I didn't know of the franchise before this movie so base my review on what I experienced on the movie and not on what I know of the franchise itself.
So from the movie the characters (Tatum and Hill) are police officers who end up screwing up on a normal job and they are then sent to work with Ice cube in an undercover programme. The film starts with laughs and action as well as minor background notice of who the characters are.
The fun starts when they are assigned to High school to find the leading dealer of a new drug being dealt around. With Tatums experience with popularity at their old high school he tries to teach Hill how to fit in with the popular, with Hill succeeding more than Tatum which then leads out to testing their friendship, the very partnership on the job as well as testing how they feel about their previous lifes in high school and what they could have now.
It is a very good movie, great charisma from the leading pair, great script, it doesn't take itself too seriously and just has fun with what their working with. The action scenes are both great and hilarious at stages and this is what an action comedy should be.
Also there is a cameo appearance by one very legend of a man and believe me he does not dissapoint :)
Great laughs, great action thrills, great acting, great chemistry, great script. 21 Jump Street does not do any wrongs but rather many rights and creates a visual experience that anybody will or should enjoy.
21 Jump Street: 8/10