Not who you were asking, but I use a Waterpik WP-100 and I'm very happy with it.
According to my dentist they are less effective than normal flossing, but I hate flossing and was never able to do it on a regular basis, whereas I use the Waterpik once a day.
I worked my way up to a fairly high pressure and it regularly removes stuff that I missed with my electric toothbrush. It also leaves you with a very fresh and clean mouth feel.
I also wasn't very sure about them when I first looked into it, but it's really not a snake-oil product. It's also not the holy grail of dental health, just a reasonable alternative to flossing.