The boots fit my daughter fine, and keep her feet quite warm. However she finds the fur a little itchy and will only wear it with socks. She never complained of itchiness with her old Uggs, which she has now outgrown. With the socks, she is quite happy with the boots and wears them all the time. So overall, the price differential is worth it.
I'll update later regarding ruggedness - she wore out her Uggs in one season (they are literally frayed and torn), so we'll see how these do.