Insanly difficult
Graphics: This was one of the early games on the SNES and it shows, however the slowdown rate isn't that bad when the screen gets loaded with planes trying to blast you into tiny chunks of dog meat. Some of the large boss enemies look spectacular for the time period. Also, they made sure and make all of the planes you can buy look different on screen, which is a plus. Also the picture of your choosen character grimices in pain when you ram into another plane or get hit by missles or bullets. And finally I think the little bits of plane that float away after you die (which you will do often) looks pretty cool.
Music: The music is fantastic in this game. It is one of the reasons I still pick it up today. Every level has its own disinct theme. I still particularly enjoy watching the opening credits, just for the music.
Difficulty: haha....this game is TOUGH I beat it once in middle school, but I have had a hard time getting close since. Emulation makes it much easier, but if you are playing the real thing....good luck ...you'll need it. Using Greg will make it easier, although your weapon will not increase as fast.
Fun: I still pick this game up ten years later. Its fun to just breeze through the first few levels to waste a little time...after that it gets very tedious, and it will stress you out.
Overall its still a great game today. Try and pick it up if you can.