Those kegs are thin sheet metal and have, as mentioned above, a micro-thin plastic liner to stop your beer getting rusty flavours.
The liner doesn't seem to last long, and I got metallic flavours really soon after using the old DAB kegs.
Maybe the kegs are different now, but I have to say that it wasn't easy to pour from them. It was obviously a matter of technique, which is certainly more easily achievable with "real" kegs, Corny or Sanke (or Eco?).
With the small kegs, you need to prime at about half the usual rate and use the CO2 only for dispensing once the pressure runs down.
Someone may correct me here, but I recall that the Beer King/ Fass Frisch keg-spear dispenser for these used to be $50-65. Not cheap for what feels like a toy (my dispenser was almost all plastic) keg setup, plus the cost of the kegs and ongoing CO2 cylinder costs. The upside is that you get to drink some DAB Dortmunder or Bitburger or Warsteiner or Tooheys (ugh...) to provide yourself with kegs.
I have a 5 litre keg of beer (from the K&K daze) that I never got to drink, and it must be at least 7 yrs old. It's probably rusty inside and the beer would be well past its use-by date, but it may be a good yeast bank for some vintage W3056.
Anyone else have mini-kegs tales to tell?
Seth