I have one with a nightlight in it. I do enjoy the soft, warm light it gives off.
Enough to see to move around and even find things in the night, but such a gentle light that it's not bothersome for sleeping. I'm not sure that I've noticed any positive effects from any beneficial ions or such, so I can't comment on that.
Being in the damp and drizzly Northwest US, I did have a bit of moisture that must have built up and caused a bit of salt to
drip or run off because I found some dried little pathways of salt across and down around the base, but it's still got it's 10-13" size and shape and I've had it at least 6-7 years, if not more.
One minor thing that annoyed me though, is some fibers that stuck to the salt leaving these frizzy bits of lint-like junk sticking up in places. If you dust it, be sure to use a solid cloth on it, not those stupid disposable dusters (which I am embarrassed to admit I bought for my son because he wanted them for his dusting chore).