No brands mentioned unless Im asked but I just love my new soda maker. I love fizzy drinks but I dont like the additives and so on that you get, lots of potassium and additives. I use my soda maker to make fizzy water from filtered water without alot of the nasties that I dont want. You can get flavored syrups too that are sugar free or you can make your own if you want. I know that alot of people dont like soda but when I want something cold and fizzy now I can have it without the additives other than the carbon dioxide shot to fizzimate the water. Yay!

My wife wants one. What brand do you have and what experience if any do you have with others?

I love mine too. Lots of fun!

I just got one for christmas and would love to hear what you are doing for make your own flavors. I was hooked on vanilla and orange vanilla seltzer and hope to replicate those and other flavors.

JohnP since you asked and as a disclaimer I dont work for the company and dont have any interest in it, I have the Soda Stream
http://www.sodastreamusa.com/
You can get it at Walmart here in Canada or through alot of other stores like Bed Bath and Beyond in the US, and you can exchange the gas canister there too. The syrups/flavorings can be bought online or at the stores, too.
I was really skeptical about the machine before I got it, but I tell you, it holds the carbonation really, really well. I'd say that my fizzy water is actually fizzier than Perrier on a regular basis. Seriously. I dont have experience with others but I did look at some but I didn't like how they worked like the iSi Soda Siphon. That one works with small gas cartridges like a Whippit does for making whipped cream. Reviews of that one say that there isnt alot of carbonation and you keep having to shake the Siphon like you do a Whippit to get the carbonation. Like turn the Siphon over, shake it, charge a small drink, shake it, charge again and repeat a bunch of times for each drink. I wanted something bigger, and the Soda stream lets you carbonate and store a liter of water at a time. Plus I have 3 reusable bottles on the go so theres always something in the fridge.
As for home made syrups, I'm a gingerale addict, so I make ginger syrup by boiling ginger chunks in water, then adding splenda until its sweet enough. I add it to individual glasses as I make it. I havent tried making vanilla or anything exotic, but if you look at the website there are tons of flavors available if thats whats gonna float your boat.

I just got it for Christmas and I love it too. Before we were lugging cans of seltzer home and then having to dispose of them. It's nice to make fizzy water when I need it.