I upgraded from a 1020 to a 950 on Saturday last plus one (11/28) ...sort of: I'm keeping the 1020's too. Significant upgrade. The phone is way better than the reviews (well, for WP peeps).
...and the iris scan is very cool.
But the 950 in general is an incremental-through-significant improvement over the 1020 at least (depends upon the area).
W10 is ...more of the same (as WP8.1), but more "fluid" (can I use that word?), or maybe refined (yeah, that's better).
Obviously, I have no plans to leave WP.
...ex-iOS, ex-'Droid user ...two years on WP ...no desire at all to change ...too spoiled by the UI.
And yeah, the apps situation kind of sucks, but I mostly voice/text/email/surf/FB/&Cortana anyways - plus I stay within the sandbox - so there's not much app-envy left at this point (i.e., two years on): what you don't know, you don't miss lol.
GSMArena.com has the best review of the 950 from the WP-centric (or at least, non-obviously-biased) perspective if anyone is interested).