The disappointment at the rumored 15-20 hours seems very weird given I just went through Paper Mario: TTYD, and that took about
27 hours. And I didn't rush through the thing either, in fact:
1) I did a lot of star piece hunting (which involved mostly methodically spin jumping and covering like every single area in the game). I even went to the fortune teller several times to get hints for that, which involves quite a few overly long animations every time.
2) I always went out of my way to get item upgrades and such, which included lots of backtracking to previous dungeons.
3) Three of the main chapters involve a lot of backtracking, and one of them is just a lot of guessing and backtracking through every single city in the game.
Not to mention that the game is pretty slow-paced compared to what I've seen from South Park so far. If this has such a quick pace like the show, I would expect a lot of value in those hours.
I did most of the side content as well, but I feel it's more important to point out the stuff I just didn't enjoy in this case. While it's not impossible this game ends up with some similar flaws, it does seem pretty unlikely given that most of what they had to do was cut content from the game, not pad it out even more. I haven't played the game so playing defense force right now might bite me back later, but I just find the current general view about the gameplay hours a bit weird.
In fact, I might've even done away with some of those extra hours in Paper Mario TTYD, given the design of the chapters gets a lot worse after
.