Really good, it's my local venue. For dressage they have 2 20x40m arenas set up indoors. Super on a more experienced horse, however quite hairy/ educational on wild 4 yr old who thinks the car parked ontop of C is an obstacle that requires jumping. One end of the arena is lined with mirrors.
The surface is good, though not that springy. I think their warmup surface is better than the arena surface. I've done both the affiliated and unaffiliated evening dressage there. Both definitely worth going to, tends to run to time and they are quick with scores.