I have no idea why IGN felt the need to rate this a 3.5.

User Rating: 10 | Sonic Adventure X360
Because I don't own a Dreamcast, I've never gotten the opportunity to play the original Sonic Adventure. So naturally I was very excited to hear it was getting ported to the XBox Live Arcade, and downloaded the game soon as it was released September 15th. For 10 bucks? One word. BARGAIN! Seriously, I daresay this game is giving me as much entertainment as Halo 3 did. The only criticism I have is the camera, which SEGA seems to struggle with throughout every 3D Sonic game. The shoddy camera is quickly forgotten amidst the fun and immersive gameplay, however. And who doesn't like the soundtrack on this game? From the main theme 'Open Your Heart' to Robotnik's catchy instrumental theme, Sonic Adventure has some of the best music of any game I've played. I highly recommend purchasing this game.

Also a little tip if you're a Wii or PS3 owner: Wii people can buy Sonic Adventure DX for the Gamecube and play it through their Wii, and PS3 owners can buy it from the Playstation Store starting September 20th.