According to reviews it works perfectly well as a tablet. Surface 2 Pro just seems so expensive when compared.
It's actually very light considering its 13inch.
The Yoga's over 1000 pounds though, whereas the Surface is expected to be 720 (sorry that should be 820 as you'll need to buy a touch or type cover as well) upwards depending on storage space.
You do however get more configuration options with the Yoga, processor, ram, storage.