I'm a fan of basically every game in this genre, but I've been particularly charmed by this one because of its sheer complexity. So many ships to choose from, each completely unique... The complex slave/medal system and 10k+ awards after those... The charming stylized 2d graphics... The simulation/real level system... I can't really think of anything that this game dishes out that I don't love. In my opinion it is certainly among the most enjoyable 2d top-down shooters out there.

Like I said, it's an arcade-only game so it's not like you can go buy a copy for your PS2 or something. If your computer is up with the times you could probably get away with running it on MAME. It's a pretty processor-intensive game, though. I play on MAME and at my school arcade.