If you've played the games you'll love this movie.
I took my two young daughters(also big Nintendo fans) to go see this and we ALL had a blast. The story is fun and flows pretty naturally (there are a few hiccups, but nothing major), the fan service is IMMENSE and very seamlessly integrated, and the voice acting is superb(and I did NOT like the idea of Chris Pratt Mario before).
I haven't been a big fan of most of what Hollywood has had to offer lately, but this was an outstandingly pleasant surprise.