I've had the opposite experience on my Windows 10 upgrade followed by a wipe and clean install. My impression is that it is a cleaned up and refined version of Windows 8.x. I rarely use mine unplugged, so don't know about the battery life.I updated my 2 SP2s to Windows 10 a few days ago and I am rebuilding both to Windows 8 as I type this...[BLAH BLAH BLAH]
Seriously...? I recall Windows 8 being received about as well as Windows ME. Windows 8 required a lot of tweaking before I considered the confusing mess of tiles under control. Windows 8.1 helped a lot, sort of like Microsoft was saying 'oops' and 'we're working on it' about the UI. Windows 10 is what Windows 8 should've been....the amount of tedious UI hack and tweaks tips you find for Windows 10 is astonishing...
I do think Microsoft would have been wise to come out with a hardware specific update install for all 3 Surface Pro lines, and it should have been released no later than the official launch date of Windows 10.