The functioning of this unit is great. It truly does make a spectacular cup of espresso on the road. The problem I have with it is the quality of its manufacture. I have bought two of these and both of them break at the slightest glance. The problem lies in the thin tube where the espresso comes out. It can break off with the slightest pressure- making the device instantly useless. This has happened twice. They could fix this easily by just making the tube out of slightly stronger metal.
We've used this coffee maker on several car-camping trips and at home on the stove. It creates a good, quality cup of coffee. We have had trouble getting the coffee to come out without sputtering and spraying coffee all over. It also seems to go through a phase of "making coffee" and "sputtering" coffee several times before completing its job. We've tested this on our stove at home, so it does not seem to be a function of uneven heating.
Ultimately, we'd love to take this on backpacking trips, but with the difficulty controlling the output of the coffee, its not quite "leave no trace" -- nor advisable in areas with bears or other potentially dangerous animals. For that, I suppose, we are again relegated to the realm of instant coffee.
But, for getting my caffeine fix for low-key car style camping events, its perfect!