Been using it for about a year now, but not in a way it's "intended to be". I wrote some scripts that add data to it and then I have a (static) website that pulls data from it and builds pages. So, for me it's more of a REST API and a web interface in front of sqlite than a proper auth provider (at least for now).

My biggest gripe with it by far is that the web interface is not phone-optimised at all, which prevents me from quickly correcting a field or two when I'm not behind a computer. For my use case, that happens at least once a week. Another gripe I have is that the search bar in the admin interface could be far more powerful than it currently is. Anything more complex than searching my records by exactly one field and I'm better off writing one-off scripts to do so than by using the web interface.

Good things: the control it gives me over which fields get exposed publicly, ability to resize images (instead of slowing down my build by doing so from the frontend), overall stability (never had it go down unexpectedly), S3-compatible storage, automated backups.

To give some sense of scale, ~10k records scattered across 30 or so tables (or collections as they call it), most with some attachments, and plenty of one-to-one and one-to-many relations between the tables. The database itself is only a couple of megabytes in size, but the whole backup (attachments included) is nearing 3 gigabytes now.

While updates happen pretty frequently, they don't change the parts I actually use, so I can't say I ever struggled with keeping up to date.