Product review (5 stars): CO2 tank change to much bigger one.
Addendum DEC 2015:  Have lived with the fridge for about a year.  Our experience has been good.  Fridge is quiet and problem free so far.  The addition of a 20 pound CO2 tank has been great. Copious amounts of very fizzy water. Did not have any ice maker leaks that other reviewer had.  One little issue arose when quests came and somehow the fridge was placed into showroom or demo mode, shutting off the compressor.  Absolutely no help from the manual.  Fix was to simultaneously  long press top two left buttons, ie., Freezer and Alarm, which turned the compressor back on. Thanks to all the people on the Internet! Why this isn't stated in the manual is idiotic.

Original review:

We bought the counter depth model.  Just the two of us, so it is plenty big.

So the important thing is my wife loves  sparkling, fizzy, gassy, water by any name.  The original. little, tiny, soda stream CO2 tanks just wouldn't do, so I had a look at it and have now attached a standard  20 pound CO2 tank with regulator, to the refrigerator, stashing the tank in an adjacent cabinet.  Works well !

So far great fridge, we haven't had any problems, but see other reviews,  all the rest is about CO2:

If any one is interested, I used 6mm PU tubing, a CO2 regulator and two connectors, to go from the 20 pound CO2 tank to the fridge. Surprisingly simple.  It seems that the soda stream regulator is built into the metallic gas bottle connector, so I just by-passed it, connecting my 6mm tubing, from my regulator,  right into the push to connect fitting in the fridge,  where the tubing from the soda stream originally connected to the fridge. Only a couple of screws need to be removed to access the carbonator and fittings in the fridge.

The tricky part was routing the tubing through the top of the door.  There is a plate on top of the door, above the dispenser, which when removed, reveals plenty of space, and I drilled from the edge of the door above the handle [ not the hinge side], into this space, through the plastic, down to above the carbonator, and ran the tubing down. All I hit with the drill was foam, but yes, i was a little nervous.

I then ran the tubing back to the hinge along the top of the door,  and underneath the plastic piece on top of the fridge and back to the cabinets.
The tubing is covered completely from sight, though if I was to do it again, I would use black tubing instead of orange. Would make routing easier.

Set my regulator to 80 psi originally, but bumped it up to 100 psi.  Works well with about 14 feet of 6mm tubing.  The PU tubing can easily handle these pressures, but is surprisingly flexible.  All parts were bought on Amazon, except 20# tank which was bought locally, filled with CO2, but everything was  about $200. I see Amazon  sells several sizes of CO2 tanks, though, of course, they are empty.  5 or 10 pound tanks may fit cabinets better. Tank has to be upright to get gas out of the top.

This review is only for educational purposes, and I would never suggest that anyone actually do it.  There is some confusion about CO2 out there though. CO2 is not under the pressures SCUBA tanks are, at least in beverage tanks, maybe 600-800 psi, and after the regulator, about 80-100 psi is used. Beverage type of CO2 is a liquid with an overlying gas phase, and not as dangerous as a SCUBA tank, which is 3000 psi gas [air].

You have to get a beverage tank, which dispenses gas from the overlying gas phase, and not a "siphon"  tank, which dispenses liquid CO2, from the bottom, which the paintball people use to refill their smaller tanks. Under no circumstances should you ever get a high pressure compressed gas CO2 tank.

The beverage tanks are sold everywhere. Always use a nylon washer between your tank and regulator. Also use flare washers on all flare fittings on the regulator. I went from a flare fitting directly to a 6mm push to connect fitting at the regulator.  Not as complicated as it sounds.  Some companies are making money off of "food grade" CO2.  Not necessary. A clean tank is all you need.

I am now looking into a small, post carbonator, sparkling water storage tank, to fit into the original Soda Stream tank space. Haven't figured it out yet.  This space is other wise wasted.