This review is primarily for snowboarders.
There are some great runs around Laax and at least two super snowparks near Nagans.
If you're riding a snowboard, you should avoid the back of the mountain near Vorab and Fuorcla. When I was there the snow was soft and deep so which is great, but forget crossing from that side to Nagans in those conditions. There are huge flat spots that around Vorab that require a lot of walking and is generally frustrating. The equipment also seems much older than on the Nagans side of the area.
I'm used to more boisterous apres ski at the end of the riding day than can be found anywhere in Laax or Flims, but apparently it gets much better at night. I found the apres ski generally boring between 3 and 7. Also, avoid Laax Dorf in the evening - there is just nothing there that I could find.
Around Nagans it is really sweet, some HUGE snowparks with massive jumps and rails. This area is really snowboard friendly with steep enough but not annoyingly so pistes. Laax also has tons of off-piste riding available and deep snow abounds if you're into that.
Had a good time, but I was new and learned from my mistakes. I hope you learn from this review and find it helpful.