I bought these for my wife as a birthday gag gift but she immediately started using them and prefers them to the bottle she had been using for years. I've had a Specialized Purist bottle for years and the new bottles are an improvement over the older models. They're functional and they're fun, what's not to like?
These are great conversation starters and an excelent gift and motivator for your friends.
Probably wouldn't buy them for myself, though, as love is best relished when it's spread as custard (see what I did there?).
I have been using this bottle for a month and it is a good bottle in that it is low squeeze pressure and good bottle volume.