Just found a different problem with online checkin.
Yesterday late afternoon, I did an online checkin for a stay tonight (this hotel offers it from the day before). Picked a room I know that's not bad (neither of the best two rooms available), confirmed my credit card details as saved with the app, and that was that.
Got to the hotel just now, and gave them my name. They flipped through the pre-printed details, pulled out a sheet, and said "Mr Gagravarr, 1 night, 2 guests, park and fly, that correct?". I replied "1 person, one night, no car, online checked-in to room 106". He and his colleague spent a bit of time looking through all the arriving guest sheets, checked a few other places, then looked very embarrassed and appologised. Someone with almost the same last name (same pronunciation, one letter different) had turned up 2 hours before, and speedily dispatched to my ready-and-waiting onlined checked in room. They had scrawled a signature on the bottom of the checkin form, but hadn't noticed the one letter difference in the name (excusable), but hadn't noticed the completely wrong address, wrong rate etc (bit less so)
I was then quite quickly sorted out with another room, a few more appologies, handed a key and here I am. Could have been a bit awkward if the others had started charging things to the room (they hadn't given a credit card at checkin as they weren't asked as online checkin had provided mine), and I'm fairly sure there'll be a problem with either the bill or the points/miles posting properly... My name isn't that common, so if you're called Mrs/Miss/Mr Smith or something that popular, you too may have this situation to look forward to!