I’d echo one of the reviews of the TaD from the NB product page: “not bad, not good.” That was basically my experience with them back when they came out in the late 90s/early 2000s. They more or less perform as advertised for at least the first few uses. The tap itself is poorly constructed and you will go through a fair share of gas cartridges, so you could debate the relative cost over time. Ultimately, it is what it is considering construction, materials used, etc. – not bad, not good.
Unless refrigerator space is the primary consideration (which, truthfully, would be one of the primary reasons to invest in this beyond initial cost and portability), a used 5 gallon corny kegging system (minus the CO2 tank) is no more than a 50% additional investment in price (typically less – shop around). If I had to do it all again, I would have skipped the TaD entirely and went directly to a corny kegging setup. YMMV.