One thing: The cop chases.
I've never played a game where cops chasing you was this much fun. Crashing into roadblocks or those moments where you dodged a nail tape by millimeters. It just felt good to play, the cops were an actual threat, it was very over the top.
Each subsequent NFS had worse cop chases. As a matter of fact, I've never played another driving game where the cops came even close.