I must agree with the preceding post.
I had early access to the full ISO and the full update, from MSDN. I have now helped quite a significant number of users to update and, in three cases, do a complete reinstall. So far, I have not encountered even the smallest hitch. Maybe I just get lucky but, as with the complaints regarding the use and installation of Windows 8/8.1, I find it very hard, in many instances, to even attempt to simulate the reported faults.
To be fair, and shooting in the dark, this was a massive update, including some minor alterations to the kernel. As with all such updates back to Windows XP, it is assumed that you cannot apply all future updates to an OS which, itself, is not full updated.
What MS could do, however, is supply updates according to what it sees as the particular platform you are using? I did think this was normal practice, and am wondering if someone in the process or writing those blogs, has got some crossed wires.