I just got one this fall, and I have only used it a couple of times, but so far, so good. I had been using a Badger 350, and also an Anthem 155. For some reason I never got the 155 to perform quite as well as I wanted, though I may not have known what I was doing. I don't really have the patience to perfect my technique to the same degree as some of the bonafide artists on this forum. That's where the Iwata really helped.
The Iwata fired up beautifully the first time I tried it, and I could paint very fine lines with only 10-15 minutes of practice. Gravity feed vs siphon feed makes a big difference for me. I turned the air pressure down low and it worked like a charm. Hey, it gives me confidence to try something challenging like some German WWII camo.
Good luck with your Iwata.