Sky certainly have livened up the tour. In previous years the GC contenders would have sat looking at each other for another week. This could mean that Sky wrap it up and the last week will be awful dull but I don't think so. I still don't think Wiggins has it in the high mountains of a 3 week tour. Whether Evans and Nibali can pull enough back is another question and will be interesting to watch. Froome though, I don't see him having any weaknesses really. He looks like he could take a few minutes from Wiggins if allowed. Wiggins doesn't look 2009 skinny which might slow him down in the high mountains but then he might be less susceptible to an illness.
I don't like the Sky tactics. It looks like they are sent out with a number of watts to hit for a certain amount of time and they glue themselves to that. But it has made it interesting so far.