In Jan, I bought a new Ultrabook that came with Win8. I immediately upgraded to 8.1 so no experience with Win8.
That said, Win8.1 blows away Win7 in both speed and stability.
My Win8.1 Ultrabook boots-up almost instantaneously.
Checking 1 box allows Boot-up direct to Desktop - just like Win7.
Prolly due to the fact the Ultrabook has a solid state disk. Virtually instant.