The power button delay issue came back for my Icon.
I used Nokia Software Updater to return to 8.0, updated to the new Verizon firmware, and then upgraded to 8.1 again. I'll post if it is better.
I love the new features, and I am well aware this is (for all intents and purposes) a "beta test," but I might go back to 8.0 if many of the issues aren't resolved with this update. Don't get me wrong, I love the Developer Program, and it is awesome to let us get our hands on new software early, but for my daily use (which is... excessive lol) the power button/wifi/battery issues seem to have escalated to a point where I'd prefer the stability to new features.
As an aside, and this is more 8.1 than Icon related, the lack of integrated social sharing (and lack of a Twitter app that you can "share to" since they pulled the beta) is more impactful than I expected. I'm used to posting interesting articles that I find online to both Facebook and Twitter at the same time, and whereas this was one click in 8.0, in 8.1 now I can "share to" Facebook (but it posts an ugly link and not a linked page style post like it used to) and then copy the text, go into Twitter, paste it, and post there. If the default Facebook share formatted links correctly and the Twitter beta was still in the store, I might be more inclined to wait it out. But we will see.