Tie::DBI is great for those occasions you don't want to really use a database as a real database and you can't be bothered with all that SQL stuff.
Mostly I don't need to do complicated SQL queries, and I'm just using a database as an abstract storage system (not necessarily on the same server) that implements it's own locking so I don't have to worry about it. DBI itself is great if you want speed and efficiency, but quite a lot of the time I need to just quickly hack up yet another script to do a quick hack and I just want to grab a row from the table via a primary key. This is where Tie::DBI comes in. Quick, simple, and straight to the point.