It's no secret that I'm a fan of CamelBak's water bottles and hydration packs. The no-bite valve is okay -- I've been using traditional water bottles for so long that biting the valve to pull it open is automatic -- but I especially like that CamelBak's bottle doesn't give my water a plastic taste like most bicycle water bottles do.
CamelBak funded a study at Pepperdine University to quantify just how much better their "better bottle" really is. They compared how much water subjects drank when they used CamelBak's bottle versus other kinds of water bottles: reusable plastic and metal bottles along with disposable PET water bottles.
In the study, screw cap bottles are compared against CamelBak's bottle with a valve, so that's either cheating or and advantage for the valve, depending on your perspective. Personally, I know I tend to drink a lot more with a valve then with a screw top container, and the Pepperdine drink study matches my experience -- the test subjects drank more water when they used the bite valve over screw top containers.
CamelBak's "Better Bottles" are not your squeeze bottles typically put into your bottle cage; they're more like the polycarbonate lab sample bottles that have become popular with hikers. They're BPA and pthalate free. Nalgene also now sells their lab bottles made with the same Tritan plastic.