Very cool, from what the trial offers. You get stages 1.1 (platforming) and 1.2 (flying/horizontal shooter) in arcade and free-play modes. It looks like they got the gameplay honed nice and tight. Full 60 fps on the Xbox. I imagine the same is true of the PSN offering (and PCs with oomph). Very smooth, colorful and pretty. I'm very tempted. I'm looking for reviews, but so far can only find previews. I guess advance copies to gamesites didn't happen? Now I feel like trying out the Genesis original for perspective.
Edit: Hah. Took me a while to remember the Genny/MD emulator of choice is Kega Fusion (Steve Snake). I had lost all my old shortcuts since my system-drive crash, and hadn't revisited Genesis emulation since. Not surprisingly, Rocket Knight is much harder right off the bat, in its original incarnation. It looks and plays great for such an old game, but it's more intent on punishing the player than letting him pull stunts with the possum. That may be why I never got into it much back in the day.