Pretty good! I put them on my 3 year old just for bed and then she uses the potty all day. I have only had a problem with them when she drinks a lot of water right before bed and sleeps in late. Other then that they work very well!
I think these are more absorbent than the pull up brand and have used this a few times overnight be prefer a regular diaper. I think it depends on your child. My daughter still urinates over night but not as much as she used to. Hope this helps!