I am really liking Windows 10 so far and boot time is insanely fast!
I haven't moved all my data back yet from the external hdds (I had to move my data onto a logical partition as I already had three primary partitions) as I wanted to dual boot. So once I have done that time will tell if they have managed to cure the age old problem of decaying boot times.
I have noticed they added a swap file, which is interesting
(if anyone is wondering, the defrag programme is called UltimateDefrag 3 by DiskTrix - Build 3.0.100.10 - I fired this up as I wanted to check where there pagefile was located, as files located nearer to the centre may have a higher seek time)
I haven't started messing around with tweaks, settings or defragged yet as I wanted to see how it felt like from a fresh install. The added bonus is that they haven't removed the setting to revert back to the start screen and the windows 8.x style app list.
However enabling this doesn't mean metro styled apps launch full screen without the title bar or not on the desktop (task bar is still visible) and snapping does not change to the portrait centric snapping in Windows 8.x. Therefore so some of the users who were keen on Windows 8.x may not like this transition.