Anyone who thinks that Tony Hawk's defines skating games is wrong, and this proves it.
Skate has always been a very open game. It gave you a whole 'city' to muck about in, where you could just skate around, annoy various strangers on the street by hurtling into them at high speed, or falling on them, etcetera... you could attempt to jump off of high things just for the fun of it, or you could attempt to complete the various missions given out by the NPC's.
Skate 2 is very similar to its predecessor, but it has been improved in almost every way. The physics are sharper and more realistic, the graphics have had a similar overhaul, the voice acting if anything is even better, and there have been two little, yet crucially important additions to the game, that were sorely missing from the first one. You can now get off your board, and move various items of scenery about the place. These two things together mean that you can now shift things like benches and tables, and ramps around the place, and create insane trick sequences and lines. And the new 'hall of meat' mode means that every time you bail, that you get marked for how impressive the bail is. There is only one problem with this addition, and that is that it is too addictive. I personally have spent hours simply hurling myself off of tall buildings and large ramps, simply to get the most impressive and grandiose bail possible, and then to play it back and laugh at my mishap on the amazing 'replay editor', that gives you a myriad of options with which you can change your videos and make them all the more impressive. I have yet to meet a single owner of this game that doesn't just use it for recording bails, though.
When you decide that you actually do want to get the storyline rolling though, the missions themselves, happily, do not let you down. As an ex convict, your character has to become the ultimate skater, (again) in a city that has taken massive steps to stop just that from happening. The missions usually involve nailing a certain line or trick, for a photo shoot, or, later on, for the cover of various magazines. These missions are blissfully short, and do not get in the way of the general shenanigans that ensue during general exploration. However, do not fall under the illusion that the game is easy. What it is, is easy to enjoy, but there are hundreds of missions and some of them are absolutely rock-hard, and will take many tens of tries until you finally crack them.
A final word, then. Skate 2 is of the most addictive games of all time, and is far superior to that flashy, jumped-up pretender, Tony Hawk's.