Hi, I just looked at mr beer and beermachine.com.
I suppose the atractive thing is it's all packaged and gimmicky and sounds ad feels easy. Thing is you can buy a 5 gallon fermenter and pressure barrel and 40 pint kit for about the same price!
As someone who is only a kit brewer at this stage, I' don't see any difference between adding 2.5 gallons or 5 gallons of water. so why not make twice asmuch beer for the same effort
If the beer machine came in a 5 gallon version I might think about it, it does look pretty cool.
Frankly though, the mr beer thing seems expensive. My Beer Sphere was only £34.99 ish and it's bigger, has a float, top tap holds 6 gallons.
The coolest thing I ever had which was similar ( and i don't know if you still get them) was a "Brew Bag" from Boots and Christmas gift catalogues. It was a plastic bag with a tap, surrounded by ultra tough plastic sacking, with a handle and came with malt/hop extract inside it. You poured in 20 pints of water and bingo, two weeks later beer! I still have a couple of the bags and have been reusing them quite successfully once the initial fermentation is done in a bin with normal kits. Good for taking to parties!