Do primer + paint products work well?
I was quite skeptical about the paint and primer combo's, but Valspar gave me a couple of gals to try out.  I was surprised how well it covered over dark colors.  The down side was that it is not as smooth as regular premium grade paints. It seemed a bit dry going on, but that is because it is very high in clay content.  I decided the best combo was to use it for the first coat and then use regular paint treated with Flowtrol for my finish coat.  The application that I would never use it on is covering new drywall. I still prefer quick drying PVA drywall sealer. The paint/primer combo is too heavy and stays wet too long for new drywall, and is about twice the price of PVA primer.