Road or mountain?
I have them on my mountain bike. They're great. Only downside is you need an air compressor to seal them initially (have to get air in fast) or you have to get your shop to mount them.
I probably don't flat enough (either with or without tubes) to notice a difference. Supposedly you can run lower pressures tubeless without pinch flatting; I don't think I really take advantage of that either. But no real complaints.