Gotta agree here. It's fun, but it's not quite as exciting as I had hoped it would be.
Apparently I do need to take a look at the Options menu more often, though.
I would put it around the length of the first game. Only took me two afternoon/evenings to beat it. U2 was definitely a longer, more satisfying game. I do have a list of complaints in the "Recently Beaten Games" thread, but there are spoilers in there, so you might not want to look at it if you don't want some of the story ruined. I may have been rather harsh on the game, but that doesn't mean I didn't enjoy it. I haven't started Crushing Mode yet, though -- I'm going to use Crushing as my "treasure collecting" playthrough as well, so I'm waiting for when my son isn't here before I start it. I missed about 65 treasures on my first playthrough.
I would say that the first and third games have about 10 hours of gameplay for the first playthrough (including watching all of the cutscenes), where as U2 had about 14. That's just a rough estimate by how long it took me to beat the games, but that's how I felt.
Even playing on Hard, though, I don't think I had to attempt any section more than five times. A couple of them might have gotten up to eight, but only because of shitty checkpoints. Seriously, there's one point where I started up in front of four enemies. Like, they were close enough to grab my cock. It was retarded. And I'm not fantastic at the game. I'm decent, but I'm pretty sure Ray, Tan and Cookie would all destroy me in multiplayer.