Good, tight plot (everything got used). Engaging characters, nice characterization, really really excellent artwork. PG for being scary in places (no blood worse than scratches and I think no on-screen actual acts of violence): nine or so should be old enough to watch it. It’s a buddy cop movie with a thought-out world. I even liked the song.
So, sure, take your kids if they’re old enough.
I just got back from an evening show. I also thought it was excellent. I didn’t see the twist coming at all.