I have an identical Windows 7 and Windows 8 install on different partitions of the same SSD.
Both User Interfaces are the same because of Classic Shell.
Windows 8 boots faster and it is generally snappier. There are many small improvements under Windows 8. Literally everything is the same under Windows 8 after proper Classic Shell installation with the additional benefit that I
can use Metro apps if want to (I don't need to - but it's nice to have that option), I
can with one press of a button switch to full Metro UI (I don't need to - but it's nice to have that option), there is zero reason to reboot into Windows 7 for me.
Whenever someone said something wasn't working under Windows 8, it was user specific... Classic Shell resolves 99% of criticisms of Windows 8. Classic Shell turns one of this thread's poster's comments upside down:
Why would anyone use Windows 7, when Classic Shell gives you *all* the options of Windows 8 while given you the option, just the option, of using Windows 7 user interface on it. Who cares what
someone else chooses to use, Metro or Classic... our common enemy are the developers who take away our ability to
ourselves select Metro or Classic, however and whenever we feel to use either, (or not.)
This is here is quote for the win:
I wouldn't tell anyone to buy 8.1 if they have 7 but since you are buying new I would say just get 8.1.