I already have Sonic 1, 2, 3, & Knuckles, and Spinball on Genesis, as well as Spinball on Virtual Console and 1, 2, 3, & Knuckles, 4 Ep 1, and CD on XBLA, and Generations on 360.
But the Steam version of Generations looks nicer and has the Casino Night DLC available which so far hasn't been made available outside of GameStop preorders on 360, and I don't have All-Star Racing, Adventure DX, or 3D Blast at all. Although as far as I know, the Steam version of All-Star Racing doesn't have the Forklift Ryo and Metal Sonic DLC, and obviously it's missing Banjo.
Should I go for it or is it a waste of cash and needlessly expanding my backlog?
3D Blast is pretty awful, IIRC. You can get that on Sonic's Ultimate Genesis Collection on either the 360 or (I think) the PS3. That'd give you a whole lot of Genny goodness for real cheap at this point.
From: Ainoxi | #005 I have a 25% sega coupon if you want it.
I would enjoy just such a coupon. I could give you a 50% Serious Sam HD First Encounter coupon for it if you'd like. Or a 50% Valve coupon but I assume everyone is loaded to the gills with those.