Florin Scanlon’s review published on Letterboxd:
Jonah Hill and Channing Tatum are one of the best on-screen comedic duos in like forever, simple as that. They sure form the best human covalent bond in the history of cinema. Both deliver equal amounts of hard hitting jokes and they're so infectious that you want to finger mouth them while they're finger mouthing you. Ok, that's taking things a tad too far... awkward moment right now... so... Rob Riggle is also in top form and his comedic moments are among the highlights of the movie. What's impressive is that the humor is not entirely dependent on cheap dick jokes, there are a few of those (and they're good as well), but for the most part the laughs come from self-referential, clever jokes and funny situations, Hill and Tatum going the extra mile in everything they do.
There's this notion that most comedies are empty and don't have anything to offer other than some laughs and light entertainment and I'd say that's - in part - true. And that could be said about 21 Jump Street as well although I think there's more to it. For example, it comments on how teenagers have changed and what was once considered cool is now deemed lame. The days of the football players are over, time for the nerds and twitter-crazed teenagers to be popular and rule the high school world. That can be brushed off as a superficially handled aspect but it's there and it's relevant.
Another important factor that I believe elevates 21 Jump Street is the relationship between Hill and Tatum's characters and this whole idea of being more to a person than what appears. Throughout the movie there's a lot of role playing, disguising, being under cover, wearing someone else's shoes and learning to appreciate what they do and what they are like. The whole Peter Pan part plays into this and there are lines that also support this transformative process, like the whole covalent bond thing and the line said by Hill's Peter Pan double, "I've been in character for months", among others. By playing against type and reversing roles, Hill and Tatum's characters become aware that there's more to a person than just a label, there's more behind the stereotype. Just because this is a comedy it doesn't mean it can't have great characters and the relationship between Tatum and Hill is pretty touching.