Ehhhhhhh.
Overhyped in my opinion. I've tried it a couple of times at a couple of different locations but came away with the same impression: burgers - nothing special, good but not great; shakes - same; fries - meh.
I'll give it another shot the next time I'm in Scottsdale and try to remember to order off the "secret" menu. Maybe that's where the really good stuff is.