Having quite extensively used the aforementioned OS for several months I've spotted a couple of annoyances:
- during the installation, initially I couldn't get the USB Wi-Fi adapter (Realtek RTL8187L-based Ovislink/AirLive WL-1700USB) working - the solution turned out to be installing it from the previously installed Windows 8.1 System folder (direct installation of the same driver intended for that same Windows 8.1 didn't work)
- probably for the same reason (certain driver compatibility issue) as the problem described under 2), an external virtual switch bound to the same Wi-Fi adapter can't be used in the Hyper-V (without rendering host OS Wi-Fi connection unusable)
- although the Windows Defender has been disabled on purpose (including disabling the Action Center notification icons, successfully stopping the services etc.), the message keeps popping up saying it isn't enabled (which is quite annoying, because in the end it isn't particularly effective anyway)
- Windows Server 2008 can't be installed as a Generation 2 Hyper-V Guest (there aren't any errors upon startup - simply nothing happens and the Hyper-V Manager says it's running, but the CPU Usage stays at 0 % all the time). However, if you try to shut it down, there's an error message saying that it can't be shut down because this is not supported (therefore it has to be turned off). By the way, it looks like it's running just fine as a Generation 1 machine...
- I've experienced many hiccups (mostly while using Mozilla Firefox)
there is no regular way of turning the updates off (which is not only time- and battery consuming - if you're using a laptop running on a battery, but could also render your system unusable, as more experienced Windows users might know from the past, due to flawed updates).EDIT (07/28/2015): Microsoft has obviously addressed this problem by issuing a tool available here.
- so far there's no floppy drive support (and some users still might need it to retrieve some old data etc.)