It didn't let the original down!
I really like the original Raiden games, and I thought that this one actually was comparable to the originals. The graphics were a little bad, and I kinda missed all the powerups and different ships that you could choose from like in the arcade version, but the enemies and level design were awesome. Maybe you should even consider making a second one (hint hint nudge nudge).
Even though I already mentioned it briefly, I did miss the thing where you could choose your ship and it has a set of upgrades unique to itself. I also missed slave ships.