The first thing you'll notice about the Power Jet is that it's pretty large. This is a direct comparison shot between the Power Jet and my old Smart Jet. Inside of the CPU-esque metal casing lies a 3.5 Liter air storage tank, and a 1/6 HP motor. The Smart Jet on the other hand has no tank, and a 1/8 HP motor. The advantages of a tank are numerous; with a tank, your compressor will have a very large reserve of air at any given time, which means it won't be constantly running. Having a tank also ensures that your air will not pulsate, and it will cool as it stores in the tank, reducing moisture.
To the right and above the tank is the air regulator and outgoing air pressure gauge. This is where the compressor really shines. The Iwata Smart Jet (my old compressor) lets you regulate your outgoing psi by way of a bleed valve. By turning a small knob at the bottom of the water trap, you can bleed varying amount of air to emulate the action of a regulator. This works, but it leaves your compressor running constantly. The Power Jet, on the other hand, uses an actual variable air pressure regulator. By turning the black knob in the middle to the right or left you can adjust your outgoing air pressure from 5 psi, to nearly 70 psi. The air is drawn directly from the reserve tank, and I can usually paint two or three parts at 20 psi before the compressor kicks on each time.
Just to give you an idea of the capabilities of this compressor, I primed all the above pieces during a roughly 2 hour painting session, and the compressor was barely warm. I would highly recommend this compressor to anyone looking for a nice upgrade. I might even go so far as to say this is the "end all be all" compressor. I don't see myself buying another one for many years. It comes at a pretty penny, and is definitely a little intense for beginners, but absolutely worth the price if you plan on doing some serious Gunpla painting. The Smart Jet is also a very nice compressor and perfect for the beginning to intermediate airbrusher. I've included links to both the Smart Jet and the Power Jet if you'd like to take a look.
Iwata Smart Jet
Iwata Power Jet