I've had very good success with mine. I'd buy another over glass. From their website:
Don't think of BetterBottle carboys as plastic – think of them as better than glass, because they are made from a special, scientifically tested, polyethylene terephthalate copolymer (PET), which does not have the disadvantages of other plastics.
BetterBottle® fermentation carboys are: are: 1) Designed to be strong, scuff resistant, easy to handle, and essentially unbreakable, 2) Pure – Taste- and odor-free, BPA-free, DEHP-free, and plasticizer-free, 3) Virtually impermeable to oxygen, 4) Clear and colorless, 5) Incredibly light weight, and 6) Extraordinarily easy to wash and sanitize (no brushes necessary). BetterBottle carboys are not at all like other plastic carboys. The special PET, used to make BetterBottle carboys, is non-absorbing, non-porous, and non-wetting (hydrophobic), so it will not carry over flavors from one batch of wine or beer to the next and it is easier to clean and sanitize than glass or other plastics.