That said, I remain a user who isn't interested in the latest trendy apps. I don't feel an urge to play Pokemon Go (although I find the phenomenon hilariously awesome). For the basics—web browsing, e-mail, text messaging, maps, calendaring—Windows 10 Mobile is great.
Continuum—the feature that converts the phone into a "regular" computer—is quite nice, although I don't use it much since I have more than enough computers already.
I am hopeful that a Surface Phone will eventually arrive and make Continuum more compelling. I could get into the idea of carrying a lightweight keyboard/display thing instead of a laptop. The HP Elite x3 already works this way.
Overall, I remain a bigger fan of Windows Mobile than I was of Android or iOS before that. When I use a modern Android device, Android feels sterile and clunky; meanwhile modern iOS feels too little evolved since iOS 1.
So, parity with Android then? (I kid, I kid....kinda.)
Of course, if you want a week on the battery, you must have data off, both wifi and mobile.
It's been solid since, but the first month or so of Windows 10 on a Lumia 950 was rough going. Store was unreliable, battery drained in ~6 hours (same hardware/usage will now last me 24+ hours), and auto-updater got permanently stuck at 0%. Only way to move to a working build was to factory reset the phone.