I think you're spot here Vader. I 've enjoyed the game myself and played thorugh 3 times so far. The amount of backtracking you have to do to solve the few puzzles put me in mind of the Dizzy games from the old 8-bit days, almost like padding the game out to make it last longer. I enjoyed the little morality tales for each character but overall their was something a little lacking that you would expect from the guys behind this game.
Given the price, I don't regret pre-ordering the game, especially as I flogged the TF2 pre-order bonuses on the Steam market for half of the price of the game.