I wholeheartedly believe that this is the BEST game on the PS2. Most people will scoff, but hear me out. Firstly, graphics are terrific. Beautiful plane models, nice scenery...it isn't exactly jaw dropping, but it is VERY nice. Obviously, it's a little dated, but it has aged very well.
Secondly, the story is extremely good, especially for a flight combat game. I dare you not to reach for a hanky after the ending.
Some other points:
Great music; "Blue Skies" is great.
Great sound; the radio chatter is immersive and sometimes amusing.
Great controls; they are totally intuitive; you'll wonder why every flight game doesn't use them.
While I'll be the first to admit that individually these catergories might not seem like much, as a package the game gels, like pudding. And come on, you know you like pudding.
Bottom line: At 19.99, you should feel guilty for all the game you're getting.