I was such a big sqlite fan that I used it for my data-intensive startup. Once I actually started scaling it up I ran into crippling file system race conditions. This was because we were hosted on a distributed file system in the cloud which I learned is very very bad for sqlite.

So I had to migrate the production db under live load from sqlite to mysql which was a quite ...intense week. I still like sqlite but I'd be wary of using it again for a usecase like mine.