I love 5-stringers and could not play without one. In general:
1 - you really need to get used to that bottom string being a B, not and E, and that third fret being a D, not a G (easily done with some practice, but it does take a little time to readjust when you swap basses with a 4).
2 - a 5 will tend to sound different, usually deeper, than a 4, even when playing the same note on the same string and fret on the two basses.
3 - the neck is obviously wider, and you do have to get used to moving your hand and fingers around a little more. One of the reasons why I love my fretless 5 is that it allows me to jump around the fingerboard with less effort than a fretted.
4 - to do justice to a 5, you need a good amp (although I manage all right with my 20W Peavey, then again, I don't play live).
Do take the plunge and enjoy!