Well I have an iPhone 5 and I said I was going to stay on 8.0.2 at least for a few weeks to see if the coast is clear. However I decided to update my phone through iTunes and perform the update to 8.1 and for me it's been painless.
I will say a few things, I can really tell 8.1 is much more polished, in fact all of the lag is gone and every thing opens and closes much much faster. When I was on 8.0.2 there was noticable lag when pressing the home button (like 1 or 2 seconds) and when I plugged in my phone with the Apple charger there was 2 or 3 secds lag before the battery icon showed up, However now since I upgraded to 8.1, all the lag is gone, battery icon shows immediately when plugged in and every thing works much smoother for me. I'm glad I updated.
Too early for battery results need to give it a few more days but I expect it to be the same, which was good for me.