My 2 cents:
I bought a new PC, Win 8 preinstalled, when my desktop box suddenly crashed and burned. I had not played with it before, and I found it awkward, unintuitive and undiscoverable. However, with the addition of a start menu program (Start8 in my case though Classic Shell works well too) and some other settings, I'm happy now -- basically because it stays in the Desktop (Win 7) interface.
To this point, there is nothing that I have found in the Metro/Modern interface that is uniquely useful enough to me to make me switch to that interface. If I had a touchscreen I would rethink - but I don't. Basically, like a lot of other software, Win 8 works great for me, and it has "features" that I don't take advantage of.
Value judgement: I had two PCs for my kids recent enough that I could get the 9.95 upgrade price. Did not take advantage of it for either.
Regarding 8.1, Darwin's post scared me off (and that accursed "Please upgrade! Drop on by the Windows Store now!" blue bar across my desktop has popped up several times so far).