My 4 year old son recently got this for christmas. The build was fun, albeit a bit long for his attention span. Overall the set is fun to play with: big truck that can carry a helicopter, some bad guys who can be locked up and broken out again.
The only downside is the one mentioned on the other reviews as well: the helicopter doesn't easily fly. I know there should be a video explaining this (although the QR code goes to https://www.lego.com/nl-be/themes/city/police/helicopter where I can't find a video), but if a kid needs to watch a video before being able to play with a toy, there's something wrong with the toy.
This launch mechanism needs a serious rethink. It was a nice try, but I feel that not enough play-testing was involved in its design.