Summary: This game is awesome. Of course it is old and therefore has some things that can be improved upon. But for the time this game came out, it certainly has many elements that enabled games to get where they are today. I would even go so far as to say this game tops some of the crap coming out nowadays. The gameplay is straightforward shoot and dodge until you get your boomerang (the spikey thing on the cover).
Summary: I really enjoyed this game. I bought it for $60 when it first came out and thought it was completely worth it. I loaned it to a friend years ago and never got it back, but I liked it enough that I recently bought it again and beat it for a second time. It's a really fun game with fantastic controls, great graphics, nicely designed levels, smart and varied enemies, fantastic boss fights, and a lot of immersion.