my iPad Air has experienced a variety of app crashes since upgrading to iOS8. Previously it was very stable. 30 GB free and , yes, I have already tried a soft reset.
All my Apps on my iPad Air are running great and this includes 1 App I have had since my iPhone 3G. As far as I know it has not been updated for iOS 7 and 8. In fact it is not even in the App store anymore. The only App I have had problem with is on my iPhone 6 and this App lost support at least a year to 1.5 years ago. They still support the iPad version though.
The only time I had an App really crash was with iOS 7 and all I did was shut the iPad off for about a minute and rebooted it and the App worked fine.