I have had a Microsoft TechNet license previously and was a beta tester for Win 7, but this time around MS has deployed the Technical Preview to the public, so anyone with an MS account may download and install it as an upgrade or as a clean install on a separate partition.
After a few days of use I've yet to experience a hiccup. Some things are reintroduced into Win 10 that will be familiar to most Windows users such as a traditional start menu and orb.
I also haven't begun to customize yet, other than my start menu preferences, browser preference, and a few apps I have installed.
As far as moving toward OSX, certainly not in the GUI, but IMO that isn't a necessity. I have both Windows and mac PCs here, both have their merits and flaws, but in today's computing world we are seeing a shift to integration between mobile platforms and desktop platforms, a place where MS desperately would like to gain some ground on Apple. That said, Windows 10 has moved away from the full on metro start screen that looked like Windows phone, and apparently was not a big hit with the consumer.
I'll keep back with any major bugs, or if anyone is interested in trying it out for themselves, I may be of some assistance.