slayglasgow.com Reviews 

First time in the venue last night seeing Spiders on Mars. From the bouncers to the bar staff the service was great. Super fast on the drinks. Liked the fact it had some seats in front of the bar as it allowed those standing to share the tables with people seated & put their drinks down and hang coats over chairs while they danced. From a gig point of view, the sound was far superior to a lot of venues I’d been in, showing the band at their best. Will definitely be back.

I've been to two concerts in Slay recently.
The acoustics of this place is not the best for extreme metal concerts (e.g. Mayhem), but it's ok for other genres (e.g. Mortiis).
The major issue was poor ventilation (after an hour it felt there's no air to breathe anymore) and it did seemed that too many people were let in too during one of the gigs (the place was packed and moving around/in/out seemed almost impossible).