Wasn't happy with the one I purchased. The switch is difficult to work, and after 3 weeks I gave up. Great company to do business with though, but the switch design is annoying at best. There have been a TON of these for sale on the forums here, and if you are really interested, best to at least get a discount that way.
The RES is a bit small, even on the ulta max. We have cartos that hold over 3ml now, and quite a few different types. There is even a 3.5 ml dual coil carto on the market. Filling the RES by dripping down the center and blowing lightly to push the
juice into ceremic is a bit cumbersome as well. You know its full by the
juice coming out the holes in the side and onto your hands or the occasional suck of straight juice into your mouth. Not my favorite system for sure. You can remove the ceramic and drip on it to fill, but again, cumbersome.
Its a very expensive mod, and for the money, there are quite a few great options with greater battery life, better switch designs, and more holding capacity. You could even go Variable Voltage and still come out cheeper.
Again though, bunches of these are being sold, over and over again. Its not a mod for everyone, and you can pick them up used at quite a discount.