I use an Olympus 45mm on my x5 and it really gets a close view from a safe distance. I have tried the 14-42 and I was very disappointed in it. It didn't keep in focus as you zoomed and the zoom action was very sloppy.
While I don't have the X5S, the X5 is essentially the same camera, just an earlier version.
I had actually put 45mm lens, the deleted the post as it isn't zoom! However I tend to agree there 45mm is a great lens, i also have the 14-42mm and dont rate it.