I'm told it can lead to fun and games if you have more than one person on the same booking, but beyond that I don't know - although that was BA's app which was updated mid-July and hasn't been too brilliant since.
I use them all the time with BA and the first time I flew out of LHR T1 using it they were unable to scan it at the security gate so I had to go back and get a boarding pass but since then (about 4 months ago) they've upgraded the turnstiles and I have no problems.
I used the EasyJet one once between Lyon and Brussels earlier in the year too - don't think it really matters on the airline - it depends on the airport having the scanners - they will tell you which ones are unavailable in the app.
Depends on your phone - I was once on a conference call at plane boarding time and its a bit of a faff getting the boarding pass while currently using your phone (I was only in listening mode, I wasn't being a complete annoying tw@t).
I use an iPhone, and if you add your passes to the Passbook app, it automatically appears on the lockscreen around the time of your flight, and you can immediately go straight to it from the log screen by swiping - much more convenient than digging around in a specific app.
I first used one of these on a flight out of City with Swiss about 5 years ago - it was fiddly as they had to email or MMS you the barcode - I'm surprised it's taken so long to catch on but I think with the prevalence of smartphones they'll only become more popular.
> (In reply to GrumpySod)
> I'm told it can lead to fun and games if you have more than one person on the same booking, but beyond that I don't know - although that was BA's app which was updated mid-July and hasn't been too brilliant since.
It only replacing the boarding pass, and every individual on the booking should have their own boarding pass so I can't see what the problem would be.