The recent Insider 'fast ring' builds download overnight and prompt you to install. The install part generally takes about half an hour, and is very much like a W7/8 install but prettier.The only annoyance was 10158/10159 in successive days.
10159 seems just about finished, though. More polished and faster than the early builds, and no major bugs. The only thing I don't like is not being able to set Google as a search engine on the new browser.
It's worth having just to get rid of the very, very, very, very annoying side-pop-out thing.