Re: Is the 950XL the last Windows Phone you buy
Beta testing is great, and it's essential, if you're working on apps or similar, for an upcoming release.
It's also great, if you're wanting to run a secondary phone, or take the "hit" of running a more buggy (fast or slow rings) OS, during release, and file bugs, accordingly. This is all good stuff, good for everyone, IMO, since beta testers are often more "tough" on the OS, in general, than the users as a whole.
What's not great, is if you're running a release ring (Release Preview) that should have all major functionality working, maybe with some minor flaws, but it's full of HUGE flaws/issues. Sometimes this is know, but I've gone back, after installing some of these builds, and have found pretty much no mention of the issues, so it's hard to know, how much was known/accepted, and how much was just lack of a real test run.
In theory, even on the regular Windows Mobile test team, they should be running regressions, against all these builds, and then they go to respective rings. As features propagate up through the branches, the same system "should" filter out the key issues, through a series of unit-tests and core-functionality tests. I used to work on some of these, more on the h/w test side, so I have some introspective, from awhile back though.
What appears to be happening, is that minimal testing is being done, in particular possibly things are getting integrated between branches, with minimal regression testing, and into the Release Preview builds, which is unfortunate, as it tends to drive people away from these builds, if they can't even use their devices for core functions.
I don't know, the Windows Mobile is definitely a "work in progress", and moving to a more-or-less singular code base was feat in itself, something that was discussed for many years, and hemmed and hawed over, again and again.
Hopefully there will be enough Mobile beta testers around, to keep up the momentum, when the dust settles ;-]