@iuzzini.
I haven't had problems with the glass..I like those better as they can sterlize with hot water. The only problem was with the caps..which soda stream solved.
I did try a (tiny) bit of salt, bicarb soda, epsom salt..just a few grains of the epsom and it made a nice mineral water. The bicarb soda rounded out the flavor into 'softer' water and was the primary addition. (as we have 'hard' water here..lots of calcium)

As for model....they've changed in the past few year. But, personally I like the glass.

Here's another item for your friend: A gram weight scale (if they don't have one).

http://www.amazon.com/gp/product/B001ODPFXE/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000O37TDO&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0HWDPKBH0DPQT7XJH1EH

Thanks Sam1148!! This article links to some German books about mineral water-- This will nicely round out a birthday present for my favorite German kitchen-scientist. :)

Also- which sodastream product do each of you recommend? I am inclined to get the one w glass bottles, but it looks like they don't fizz as well (and lose their fizz quickly) and apparently the little carafes break easily?

I love mine, too, and like to mix with tiny amounts of fresh citrus juice or True Lemon right in the glass (not the bottle). A friend turned me on to flavoring with fresh mint and slices of strawberries and pitted fruits. Put the fruit in the glass, "muddle" a bit, then add the bubbly water. It's subtle and refreshing.

Oh well..a triple post for me. But some might find this interesting, if you're the science type and have gram weight scale and want to reproduce 'mineral water' with soda stream.

http://blog.khymos.org/2011/01/30/diy-mineral-water/

Article includes a link to a spreadsheet for calculating adjustments to your tap water to reproduce popular brands of mineral water. No, I haven't tried it myself---yet.

Speaking of flavorings: Has anyone tried the Italian soda syrups? If so, what flavors and what brand?

I second the customer service from Soda Stream. The Penguin model came with glass carafes and twist on stopper tops. Both started 'hissing' no matter how tightly I sealed after a year. I though "well, I'll order some new ones". Sodasteam asked about usage if I had put them in the dishwasher etc..and sent me two new stopper tops free.

Oh - I should also note how terrific their customer service is. My original Soda Stream maker finally gave out a few years ago, when a young house guest got a little ambitious with the buzzing, and blew a gasket seal on the carbonator. I had already had the thing for at least 4-5 years. I called Soda Stream to order a new one, and ended up speaking to someone to see if they had replacement parts first. Soda Stream sent me an entirely new soda maker overnight at no charge - no questions asked. They know it's in their best interest to keep you buying the gas canister refills, especially if you're a loyal consumer, and I certainly am.

We absolutely can not keep SodaStreams in stock! In the year and half we've stocked many different models, and I have never heard a single complaint. In addition to customers absolutely raving about theirs, every staff member we have has one and loves it! We also have one for the store, that we demo for customers, and make tons of seltzer with!

There are different models and options to fit every budget and style - from plastic (BPA free!) to glass bottles, to stainless and plastic bodies. Additionally, SodaStream makes many different flavors that you can add to make such drinks as cola, orange and lemon-lime.

One important thing to keep in mind, however, is that SodaStream can ONLY carbonate water. Then, you can add flavor/juice after its been carbonated. If you attempt to carbonate a juice/water blend, it will explode and make your kitchen a sticky mess! If you wanted to use it for this purpose, I recommend the old-fashioned style siphon by iSi.

Hope this helps! If you have any other questions, feel free to ask away!

Also, Kristen, food52's Senior Editor, wrote this story about seltzer systems in the Wall Street Journal: http://online.wsj.com/article/SB10001424052748703794104575546381781963968.html

Ditto what stack said. I've had mine for more than 7 years. I go through about 2-3 bottles per day. I don't use the flavorings, make my own. fresh citrus (orange, lemon, lime) are my favorites, and I LOVE cucumber and strawberry. Drinking some strawberry water right now!

Just bought a Soda Stream -- very happy with it. In fact, I'll soon be doing a blog post about some of the drinks I've made with it.

SodaStream is fabulous. We make about 2 bottles (1litre each) per day, a canister lasts 40-45 days or so. Cheap, convenient, and environmentally sound. Agree with above, that the flavorings are not so good -- almost all of them contain artificial sweeteners, and the few that don't aren't tasty. We typically mix the soda with juice if we want flavours. Where we are, for whatever reason, the carbonated results tastes a little bit off if we don't filter the tap water first.

I agree with Sam1148. We use ours daily, but only for plain seltzer - didn't care for the flavorings.

I use my soda stream quite a bit. It's nice to have soda water on demand.
William Sonoma sells the high end Soda Stream (the penguin).
Bed Bath Beyond is now selling cheaper models. (a good use for the coupons they send you each month).
Both sell the recharge C02 at the customer service desk with exchange for the old cylinder for about 15 dollars; which makes about 60 liters of soda water.

Avoid the flavorings (IMHO) as I really don't think their good.

Excellent, use it all the time. Allows flavor without junk.

A friend of mine has one and swears by it. If you drink enough seltzer it pays for itself pretty fast.