I enjoyed every minute (which sums up for three whole days)
About the characters – I loved them all. Each of them is great fun; you really appreciate their different abilities and use them all. The abilities which you gain during the game are also great, and for a change (I don't know why) I liked the fact that you don't get so many options to choose from (whenever your character gains a level).
Once you start playing you can't let it go – but that's just not enough.
About the final level (maybe it's just me – I believe not, others had suffered from this) : It was extremely hard comparing to the entire game, which made it even harder (since you get used to a fair level of difficulty throughout the game).
The second thing is that this game is too short. I've finished it within three days, and that was it.
Bottom line, you really should play it – it was a lot of fun (but like all good things it'll end before you'd notice).