I have been here a few times either to check out bands or for bar nights. It's a good, midsized space for that in between sort of act....not not famous, but not really famous either. One of those places where if some act gets really huge, you can be all "oh, I saw them at the Garrison years ago."
The sight lines are good -- it's basically a box of a room -- and there are benches around the sides of the room. The sound-guy space (that's the technical term) is right beside the bar, so if you like to drink, you will also get to enjoy the acoustic sweet spot.
Beer prices are reasonable for cans, and the bartenders are quick and efficient.
The toilet situation is not ideal, though it sounds like it would be: unisex private stalls. I think there are around 5 of them, and the night I was there, the lights were broken in two so they were unusable. I recommend heading to the front part of the venue to use the bathrooms there.