It was the first game I rented from a Blockbuster (on the grounds that I wasn't fully sold on it) and I didn't think it could've let me down more. Nice concept, really lackluster execution. I was also astounded by how linear and claustrophobic the levels are, especially for a game about parkour.
See that's why I'm saying a sequel would be awesome. I would imagine it would improve on all of those things. Lord knows the gun the combat could afford an upgrade or two, haha.