I use them all the time and prefer them over the Platypus Softbottle. They have a pleated bottom and are made from a stiffer plastic, so they "stand up" on their own better. The cap is to the side/corner instead of the middle, which I find more convenient for filling and pouring. Mine weigh 0.8oz on my scale, compared to the 1.3oz Platypus Softbottle.
I have about 6 of them, purchased over the last 5 years or so. No durabilty issues at all. I've flown with them filled and in my checked luggage (they're marketed to the cruising crowd for sneaking booze onboard.) I've packed them deep in my pack for dry camps without any problems.
My experience with ordering from Easy Traveler (Rumrunner) has been very good; they usually arrive within days of ordering.