I remember playing the demo and not liking the new character(s) very much at all. YAGS and ZAGS were great though, of course. Before I purchase this game, because I want to give it another chance, does it ever mention the old characters again? Like do we hear about Elliot, Steve, Robert, Hannah, Chris, etc?

There are mentions of Chris, James, Jake,  Nate, and Dan, and there are a couple fics dealing with Elliot, but they are definitely not the focus of the stories here (which really center around Adam, Carlos, and Nick)

If you're more interested in the other characters, you might want to check out the ZAGS companion fics rather than AAGS: http://zags.bobcgames.com/zagsfics/

I'll also note you can read the majority of AAGS for free here: http://aags.bobcgames.com/aagsfics/

(The game just adds backgrounds, sprites, CGs, and a couple new chapters)