Yesterday, I upgraded three systems - one i7 desktop and two i7 notebooks - to Windows 10 Anniversary (from Windows 10, which were previously upgraded from Windows 7). Silly me - as I was low on disk space afterwards, I did the disk cleanup and deleted all the old versions and install files.
The i7 desktop started freezing up a lot - I checked the system logs and saw lots of I/O timeouts on the disk subsystem (Patriot Ignite 480GB SSD). I rebooted, it seemed OK, so I downloaded the Patriot disk utility and updated the drive's firmware. The drive toasted - the system won't boot, etc. I'm trying to see if I can get Patriot Memory to replace the drive.
One of the notebooks (am writing this on) is an HP 2540p - i7 2.13GHz, 8GB RAM, Crucial C300 256GB SSD - have noticed pausing on as well. Checked the system logs - see several instances of disk timeout, retries, and resets here as well.
Log Name: System
The IO operation at logical block address 0x11f64b30 for Disk 0 (PDO name: \Device\00000037) was retried.
Log Name: System
Reset to device, \Device\RaidPort0, was issued.
I contacted Microsoft - they basically gave me the link to create the .ISO file (they claim it's the Anniversary edition, but I don't know yet) and said I could use my existing Win7 or later keys to activate Win10. Never mind all the lost time or data, nor the toasted SSD (my fault, I suppose) involved.
Based on what I am seeing on these two systems (third is same notebook as second, but with Intel X-18 160GB SSD vs the Crucial in this one - and I haven't checked it yet) - I would not advise anyone I know to do the update to Windows 10 Anniversary edition until this issue is understood/resolved.
I'm also (one of the few) with Windows Phone 10 (Nokia Lumia Icon) - doubt I'll be updating it to the Anniversary edition any time soon.