T.R.
My husband loves his. He makes his own flavored water for work. We have fewer bottles to recycle since he reuses the bottles everyday. Yes the soda stream bottles are expensive but he has been using the same ones for a year.
As a treat or for guests, we use the regular, not diet syrups. Not often but it is fun for the kids when they have friends over. So much better than all the high fructose corn syrup in name brand soda.