I see a common error from a non-developer perspective, the error is : ‘it’s a preview, so bugs are expected’.
Bugs are not equals at all, there are 0-grade bugs, 1-grade bugs etc etc.
A 0-grade is a bug that manifest itself when using a functionality as intended and using only that functionality; 1-grade bugs manifests when you use a functionality but only if you have 1 specific case, 2-grade if you must met two specific cases for trigger the bug etc etc (i’m italian, this could be explained better from an english native speaker..).
0-grade bugs should not be present in the code in any state, because they must be addressed by the developer during its test, 0-grade integration bugs must be identified by the QA and addressed by the developer.
By my experience 0-grade bugs are released in a software in large quantities when the developer are under pressure and don’t have the time to fully test their code.
I have not tested the latest alpha 2.0, but i think that login problems or crash after 5 minutes are 0-grade bugs and this could be a sign of a rushed develop cycle.