Man, I mean I love the game for just about everything overall, but now I gotta single stuff out? Aw man.
1) Overall gameplay. Growing up my two favorite racers were Extreme G and F-Zero. Wipeout is more or less the combination of and improvement on, everything that was good about those games. Speed and movement of F-Zero with the tracks and weapons of Extreme G? Yes please. (Yes, I'm aware that Wipeout predates Extreme G. )
2) Customizable options. Prefer the old HUDs to the new HD one? Change it. Don't like the Fury Menu as much as the HD menu? You're nuts, but change it. Not to mention the almighty Custom Soundtrack. Few, if any, games have put this much effort into the small details that allow the player to experience the game how they want to.
3) Online play. Now this day and age that's sort of a given, but it's still awesome. Most of the racing games I was hooked on previously were older, so all I had to race were my friends, and as awesome as that was, now I can race anyone in the world. Badass. Not to mention how well the online system actually works. No problems like horrible lag or anything despite races having people from all corners of the world blasting along the track at mach 1. If only Armored Core's online play was this sturdy.
4) Difficulty. This game does a great job of easing new players into the game and letting them get their bearings without making them demolish their controllers in frustration. And even if they do get trashed, it just makes them want to come back and try harder. But on the other end of the spectrum, there's more than enough here to keep the elite players busy and their skills honed and tested to perfection.
5) The price. Everything that was said above, and for the third of the price of a regular game? And a whole new expansion for half the price of that? There's gotta be a catch.