We use these sleepers all the time.  During the cooler winter months (we're in CA), baby will spend a lot of the morning hours in one of these. They seem well made too.  I love the convenience of a zipper which makes putting on and changing diaper very easy.

My only negative would be sizing. We have the 0-6 months which is already too small for our average size baby.  I would say 0-6 months is probably good for 0-3 months.  We bought the 12 month for baby less than 6 months.  You really can't beat the price either.