In all the talk of graphical downgrades no one seems much preoccupied with 'why?'. Why build something and then proceed to tear it down, piece by piece, in the hope that ever more diminished expectations about the final product won't be severe enough to...
The Good: Great graphics and audio, does everything about shooters really well
The Bad: Only 8 levels, the levels are really short, not much in variety, no story
I'm not very good at older shooter and platformers, but I was pretty good at Raystorm. I got through 6 of the 8 levels without dying on my first try. Raystorm sports awesome graphics with tons of effects on screen with no slowdown. Most arcade ports to the PS1 were not very good, but Raystorm is an exception.
You have three different weapons at your disposal. Your regular gun, lock on missiles, and a special attack that clears all enemies on screen. While this is pretty standard for all shooters Raystorm does it well too. Raystorm doesn't do anything spectacular, but it does everything you know very well. The biggest downfall are the short levels. You can beat them in about 5 or less minutes each and there's 8. You can blow through the whole game in less than an hour, but it's even more fun with a friend. You can pick this up on eBay fairly cheap so those shooter fans should take a look.