When I got my second bass after a year or so learning I ended up getting a 5 string. I've always liked playing low so it seemed like a good idea.
I found it only took a few weeks to get used to the 5th string being there, and also that playing normal four string lines felt more consistent, as I had something to stop my finger after plucking the E string.
For me I just think it makes things easier. I often prefer the sound, and definately find it more comfortable playing higher up the neck, and 5 strings means I can play lower lines higher up, so thats a bonus. Being able to throw in those really low notes is cool too, in the right kind of band.
I find mine easier for fast fingerstyle stuff as the strings are much closer together than my 4 string, but its harder to slap on. That depends on the bass of course