New OS are like new cars: skip the first model year
You've heard the warning to skip the first model year of any car, right? The same applies to the first 12 months of release of any OS. It generally takes that long to work the bugs out, and it sounds like there are plenty in iOS 8.
I waited that long to go iOS 7 in my two-year-old iPad, and I didn't seem to have any problems. The other day my son asked if we shoudl go iOS8 on our newer iPad mini, which he mostly uses, and I said "not yet" even before hearing about all this. Glad I trusted the lessons of history.