You may not have a choice: I just found that my copy has been updated automatically. Reportedly this update was released “inadvertently” and wasn’t intended to launch until iOS 8 arrives in a few days.
The reason I know this is that the update in the App Store says so. It also says that people have been finding problems with it on iOS 7 and that therefore The Omni Group is working to resolve things.
But in my casual use of OmniFocus 2 for iPhone tonight I’ve not hit any snags. Plus, I’m updating to iOS 8 the instant it’s available so the worst that can happen is that I stick to OmniFocus on my Mac and iPad for a little while.
So. If you can avoid the automatic update, do. If you can’t or you haven’t, hopefully it’s a shrug. But at least you’ll know why if you hit a snag suddenly.