I enjoy them aesthetically... All the color and pattern differences... Also the bone structures too... My first reptiles were crested geckos. I always thought they looked like mini dragons. I love the way they move (if you've never felt gecko feet on you, it's pretty cool and the first time I held a snake it felt even neater than that).
I love having something different, something non-furry. They don't smell and don't make noises, so very different from small furry creatures. I also enjoy teaching others about them. I have 2 geckos as class pets and can't tell you how many of my school kids stare into the terrarium each day to see if they can find where they're sleeping, etc. and then ask me questions about them.
What do I not like? My main issue is when there's something "off" with them that I can't fix... i.e. when my male hognose decided not to eat for about 2 months with no notice and no discernible reason. I've not had a major health scare yet... but anticipate lack of knowledgeable vet care to be an issue too.