I think a lot of the flack it's getting is down to the behinds the scenes drama and the bad timing of putting it out at a point when new Star Wars is about the last thing anyone wants. If this exact movie had come out instead of Rogue One I bet it would've been a lot better received.
I mean it's not amazing or anything but it has a bunch of entertaining performances, and I even thought the backstory they come up with for Han and Chewie pretty much makes sense. It's harmless.
It does however end with a cameo that's so brutally stupid I honestly could hardly believe what i was seeing. Something straight out of the fanfiction of a complete moron.