I always check-in using the app and use the digital key only ~ 90% of the time. When traveling with my wife or family I'll stop by the desk to grab some hard copy keys. When traveling solo, I never bother going to the front desk unless its a hotel I might want a meaningful upgrade. I have been upgraded at the desk after checking in on the app (but rare). I still get the 72 hour auto upgrades a good bit. I never check in the day before arrival, when the app pings me to check in. I always wait until day of arrival to check-in since many of my business bookings can be cancelled up to that point. Sometimes I get "we don't have any rooms to show you right now" when checking in on the app, but almost always I have plenty of rooms to choose from. I frequently get an alert on the app that my room is ready 1 or 2 hours before official check-in time. I've only had issues with online check-in/digital key maybe 3 times in the many years I have used them. And those were very rare cases where the hotels had a power outage/their system was completely down. I don't think the Hilton app will win any awards, but it is functional enough for me.