Well, to me, Limbo is more of a platformer than a puzzle game actually. And yeah, it's great. It is a tad on the short side though, having it played from end to end in one sitting of approximately 3 hours.
But then, I rather have games end when I still enjoy them than having them drag on forever until i lose interest. And 3 hours for 12€ is quite okay.
Oh well, let me rephrase that: 12€ for a game that takes 3 hours to complete, but is available for me to play as often and as long as I like from purchase until I either die or the digital distribution plattform ceases to exist, for no additional charge.