I think the gist of it is that the Democrats are unsure how to deal with him at this point. He doesn't fit the Romney template. I think he is going to be a strong contender in the primaries. Considering the track record of the establishment GOP presidential candidates the non-establishment GOP primary voters will want someone to beat Bush. Walker has won some tough fights and he gets things through against serious opposition. This will appeal to the Tea Party wing.
He doesn't have serious opposition. The state senate & the assembly are republican majority & have been since he won office. They've all been sucking each others dicks since 2010.