Yes, for some images it's a handy extension to an already-good feature. You should also find panoramas are faster - Adobe say it's merging, but I see most benefit in previewing.
Adobe also restored a small feature that used to be in Lr. In Export you used to be able to conveniently select Home, Documents, Pictures folders, but this was dropped in Lr4 because of Apple's App Store terms. It's now back.
John