I've been a serious lifter for 14 years and a member of this 24 Hr for 1 1/2 years.
Overall its pretty good. I train right at the peak time of 6PM and with the exception of the odd time not having an open treadmill for me right when I want it I rarely have an issue getting the equipment I need. It's kept pretty clean and the equipment is maintained well. Rates are reasonable and the front desk staff are very friendly. Huge lot so there's spots even at the busy times, you just might have to walk a little bit. Oh and not gonna lie. a ton of ASU scenery is easy on the eyes ;)
Here's the negatives: Never any paper towel in the locker room, at least 5 treadmills are down every day, dumbbells stop at 120lbs (not an issue for most people), and it's pretty hot in the summer months (although I don't mind that since a cold gym is hard on your muscles when you're going really heavy), lots of goofy little ASU dudes who cut up their t-shirts into string bikinis to show their non-existent muscles will make you laugh and trip on the treadmill.