Hmm it actually got great scores from Game Informer and Chead Code Central, but that is almost it...
I agree with one review quote there: "I really want to play Knack 2...Not because Knack - a cartoonish and linear fantasy brawling adventure for kids - is an amazing game that left me dying for more of the same, but rather because it had the potential to be an amazing game."
Knack is a very good game but could've been amazing.
I felt the game dragged on for a bit too long. I recently got to the level where the trolls were attacking the city. By that point repetition set in and I was ready to call it quits. But as you mentioned, iron out a few things and the sequel can be even that much better.