EXACTLY everything I wanted it be. As a nostalgia player of the original game, this was the absolute perfect collection!
I never even heard of the extra versions of Xevious they include, but they're excellent updates to the franchise, just like the newer remake of Missile Command was for the PC and PS1. The original arcade version on the PS1 is *EXACTLY* how I remember the original was, though I immediately ran out to buy a good solid arcade-style JOYSTICK once I found how unsatisfying the DualShock2 controller was in my hands. Once that was obtained, I was in heaven.
I haven't played it a LOT, since I've got a ton of amazing games I'm still trying to wade thru, but I'm definitely happy with it. I'll be playing this, with fond memories of my olden days as a stand-up arcade player, sitting down comfortably in my sofa, for many, many years to come. :)