Sadly with today news on the restructuring of phone division in Microsoft, haters gonna use this as reason why they shouldn't bother with Windows app development. But honestly I was hoping Microsoft will clamp down on the crazy number of phones they release also in a year, way too many, so many like not much distinct differences from one another in the low to medium end till confused ppl.
Ya, Xaramin that was shown in BUILD was basic stuff, they still working on it. By the time Windows 10 for mobile ships it should be much better. Unfortunately not sure if anyone gonna be interested anymore by then after today news.
I have W10 running on my L535, pretty stable this build but ya, don't use it as daily driver. Yes the trick to update to WP8.1 Update 2 is gone, this is because of ppl being idiots complaining bout not able to get W10 when they enroll in Windows Insider. So Microsoft decided to skip that prerequisite in the latest W10 build.

no it wont, its just a critical update to fix random reboot.