Besides being hilarious, for a comedy, this film is complex.
On the surface you expect it to be a film about a couple with a baby, who have a frat house move in next door and get caught up in a war with these college students - and it is exactly that. However, beneath the surface lies an Ogre/Onion like film. It has lots of layers.
From one perspective, you have the Seth Rogen and Rose Byrne's struggle to get these Frat boys out. From another, you see Zac Efron and his peers trying to fulfill the legacy of their Frat - Delta Psi. From another perspective, this film seems to tackle many emotional transitions that we go through in life: childhood to adulthood; adulthood to parenthood; divorce; friendship - need I go on? All while maintaining it's comedy status and never drifting from the backbone of the plot - this war between neighbours. This makes the film relatable to so many age groups.
The cherry on top is the cast - Zac Efron provides the abs, Seth Rogen provides the weed and then other comedy stars such as Dave Franco and Christopher Mintz-Plasse create that archetypal comedy feel.
A personal highlight is the Robert De Niro party that Delta Psi host - Franco's impression of Jack Byrnes from the "Fockers" series is particularly accurate and therefore side-splittingly funny. There also seems to be a blend of simple puns and jokes and some slightly more subtle jokes throughout the movie.
One negative for me would be Seth Rogen's narration of his sex scenes, repeatedly reminding us that this is "spontaneous" and "crazy" - some may find it funny, I find it awkward and if anything a little weird. Other than that I can't pick much wrong with it.
Stoller has created a dynamic comedy - it's everything you expected and everything you didn't.