12-15 years ago. They had a great time there, but most went there for a specific program and really stuck to the active Mormon community (which revolved around the institute program).
There tend to be enough members in/around the surrounding area that you're pretty well supported, but it's not for everyone. ASU is very much a party school with a strong Greek scene, and can be very isolating if you don't find your people (either in a fraternity/sorority or at institute).
The two or three non-Mormons I know who went to ASU all have problems with recreational drug use (but are in high-earning careers and are nice people).
The Mormons I know who went there are doing just fine.