This is decidedly US-focused, but a nice write-up on some of the key features of airline apps in the WSJ:

Click the link: http://www.wsj.com/articles/which-ai...ier-1435772320

Or google the title: Which Airline Apps Make Flying Easier?

I'm a big user of airline apps for check-in, boarding, flight status updates, seat changes, etc. I have to say that I find the United app pretty functional and robust. There are a few things missing with the AA app (seat changes, for example). The DL app seems pretty good. Did not like the AC and US apps at all.

Are you big airline app users, and what do you wish your primary airline's app would implement?