Admittedly, I'm not so fond of them. I mean, I'm ok with people who have them, but I personally don't like the concept.
I suppose that it's just the neon colors clashing, and to people with sensitive eyes or astigmatism (I have both), it can be painful to look at them.
I do like dark red/blue/purple bases, with the right markings or non-clashing color scheme, but other than that ehh.