ASE 2-3 might be just a little too gonzo for me to use it out of the box. That doesn't mean that I won't steal from it liberally, though.
I think my favorite thing is the Scientist character class. I think the class is really more of a Cyborg than a Scientist, but some of the lore-type abilities might combine nicely with the Techno-Rat class from Sword+1's "Resistance" B/X hack. It also gives me an idea on how I might revise the Headhunter and implement the Combat Cyborg in my RIFTS-to-AD&D conversion that sits mostly finished on my hard drive.
If there's one thing that I truly take away from ASE, though, it's the variety of stuff in the rooms. There really is never a dull moment in ASE. I would totally play in an ASE game, but I'm not sure if I would ever run one.
....well, except at a convention, maybe... or a "we want to play but don't have enough people" type of thing.
I still think it's money well spent, though. There's a lot to observe about dungeon design and making rooms memorable.