I've been on iOS 8 since June. It has a lot more functionality than iOS 7, I think most who update will like it.
One of the neatest new features is being able to make and receive phone calls on your Mac and iPad, relayed through your iPhone when all devices are sharing the same WiFi network.
Mine took a very long time too, For about 2.5 hours I had a message saying my request for the new software had been received, Then it started downloading which took 2 more hours, It all went smoothly but took far too long.
I'll update my iPad 2 tonight but I'm keeping my 4s jailbroke on 7.1.2. I'll go to 8 if/when they jailbreak it. There are still just a few customizations I just won't live without unless I have no choice. (no sent text sound when phone is on loud, asktocall <no butt dials>, springtomize <hide news, stocks etc>, and I really like androidlockxt instead of the numeric or work pass lock). If apple would let us do simple stuff like that I wouldn't really need to jailbreak