One of the reasons the developers were upset was because they spent a lot of time working lengthy hours the past few months to get the game ready for Wii U's release...and then it was delayed to port the game to two new versions. Now on top of that those same developers have to make another exclusive demo and this standalone mode (or are they the same now?).
It seems like they are adding more work to the developers who were angry about how much work they put into the game before it was delayed.
On the fan side of things, this doesn't make up for the delay. It's cool for people like me who weren't going to get the game anyway, but this just all the more emphasizes the fact that the Wii U game is done and just sitting there until 360/PS3 versions are complete. Yes, now they are supposedly adding even more levels, but it's not like the game would have been lacking in content had it been released next week. This added content could've been DLC.