Windows 8.1 updates has pretty good features which attracts but it doesnt contain lot of feature as expected.
Windows 8.1 requires Video Graphic driver properly installed. If you install Windows 8.1 from ISO then it will install a seperate and fresh installation which will let you install all the softwares once again. Which is quite tiring. Also Windows 8.1 requires NS enabled from your bios settings. If you didnt install contact with your administrator or get a updated bios update from their manufacture website.
Remember this update is not that stable and has many issues which existed Metro applicaiton which crashes most of the time. If you are lucky you might get some application which will work fine with Windows 8.1.
It is more frustrating when Metro Skype application crashes. you might found some fixes from internet about graphic setting but this is not going to work at all.
Conclusion: Please don’t update Windows 8.1, Its not stable and surely will disappoint you.