Having gone from 6.x JB to 7.x JB on a Mini 1 in August, and then stock 7 to 8 on a Mini 2 last week...
For me, the plus to 8.1 is app supported NC widgets and extensions for using apps like 1Password directly in Safari. This is huge for the way I use my devices.
The minus is that 8.1 is a bit buggier than 7.1.2, which in turn was worse than 6.x.x. (And I haven't even experienced any of the bigger bugs.) Spellcheck is now worse than useless with contractions (the new predictive keyboard function helps that though; I finally turned autocorrect off).
I too have no use for Continuity or Handoff. Even so, the pros outweigh the cons for me. I've seen no battery issues and little perceptible change in performance speeds...but the Mini 2 is a newer device. I'll be interested to see what happens when I upgrade my iphone 5 this week or next. Waiting for the polished JB to be released and for a couple of tweaks to be updated first!