I've got to hurry and finish this review so I can get back to playing THPS4.
1. Challenges: challenges based on silly individual situations with no linear storyline leaves the game wide open.
2. Soundtrack: remarkable soundtrack with a great variety of songs. Although other later Tony Hawk games have larger soundtracks, this one is easily the best.
3. Stuck to the board: I do believe the ability to leave the skateboard is an improvement for this game, but there's a certain fun to the challenge of getting on top of a building without using your feet.
4. Videos: I only add this because of the incredible Rodney Mullen video, etc. They're a fun addition.