Hear me out.
The things my generation will feel nostalgic about are often not the best, most creative, wholesome things out there. Like most mainstream pop music in the last twenty-ish years. However, I'm glad to have grown up raised on the best from Pixar and other great movies like the Lego Movie. Angry Birds is a movie that me and my siblings have watched probably around thirty times, and therefore I know that in twenty-ish years I'll look back on it with a lot of nostalgia.
Does it deserve this?
Perhaps not entirely.
Nonetheless this is not a bad movie overall and does not deserve 40-ish percent on Rotten Tomatoes.
The problem with a lot of reviews on sites that like is that they are all written by adults, who of course viewed the movie with an adult perspective, when the target audience for this movie obviously was not adults. Not saying that an adult can't enjoy this movie, because they certainly could. I do, and I am very nearly adult (three weeks away--augh help). The storyline of the movie is a good one. There are a lot of good jokes, and only a few potty humor ones. Also for a kid's movie a lot of the jokes, especially the ones told by Red, have a really sarcastic tang to them, so much so that you'd have to be a certain age to really get a lot of them. But this movie, like a lot of kid's movies, does a good job of having jokes for young kids, older kids, and even for adults. Also it can even be a learning experience! In the scene when a mom bird vomits into her kids' lunch bags, you can explain to your perhaps a little confused younger children how mother birds do actually vomit up their food for their young chicks.
And if you want to put your own even funnier spin on a certain part of the movie (the montage of Red, Bomb and Chuck trying to get up the mountain to see Might Eagle), you can imagine Red is an older sibling and Chuck and Bomb are the younger siblings. You'll find it's a very accurate representation of any time older and younger siblings do anything together and it will make you literally die laughing. (that is if you have siblings...sorry only children. This can be educational for you! Or maybe you have cousins that you can picture this happening with).
Anyway, the movie also does a good job of developing an actual story--and a good one at that--from an iPhone game, which is an impressive feat. Turns out there's more to it than random pigs stole random eggs from random birds and now the birds are trying to get their eggs back by destroying the pigs very rickety and not at all well designed structures.
So yeah! Definitely recommend, especially if you have younger kids and are looking for a good family movie that you also can enjoy.