Good value? i beg to differ. i almost got one, but balked at the fact that it was really a $200 battery holder with a few wires inside. Remember that when you compare prices with the Quantum systems, the Quantum comes *with battery*.
That said, i have tried it and admit that it does serve its purpose. The flash recycles much faster (than by itself), and if don't want carry a lead-acid battery on your waist, or insist on AA batteries, this is just about the only way to go. Still, $200 for a piece of plastic...