Great movie, well made, well directed, well acted. A really well done story that makes what came before even more emotional.
If you have young kids, you might want to read an in-depth review. It's Watership Down and Maus levels of dark in parts. 13 and up should be fine.
I see some of these reviews were upset with how depressing and upsetting some parts of the movie were. The start of the first movie was a kids mom dying of cancer right before that kid was abducted and raised as a criminal among space pirates. Then we meet the rest, an Earth animal experimented on and tortured. Groot. An Assassin taken from her parents who were just killed by Thanos, to be raised as an assassin for him as he tortured her new also taken sister. And Drax whose family was all killed. Animal cruelty hits harder then human suffering in movies most of the time. But this trilogy has dealt with dark depressing things it's whole run, it's what make them grounded and feel real as we follow the characters around very colorful and interesting space worlds.