I checked it out, it is also a beta site and it seems about the same to me. On our home we just sold it gave a range of $100k and the middle of the range was just under where we had sold it. It did seem to offer more similar comps than zillow in our case. Hope that helps.

I just ran a property- our old home.
It came up $174,306.. to.. $205,066.. to .. $235,825.
Zillow lists it as $266K.

This home just sold for $300K.