I saw it in this way: 

* I won't have to setup the container in every test method (start using it right away, because it's ready for me), 
* I don't have to bother with stopping the server (and possibly leaving a port reserved, although, I have to confess :), in my tests it never happened, but I didn't have time to investigate how and where that happens), 
* I saw a few large try-finally blocks (in order to stop the container) which I wanted to bypass.
* This test class has a number of test methods, so when others are finished, it may be that the number of LOCs is nearly the same, with some of benefits of the above.
Again, only my view of it, still haven't developed an embedded checkstyle in my eye.:)