I own one.. And I would give it 2.5 out of 5 stars.. The unit feels a bit clumsy and awkward in your hands. And by that I mean that I find myself cradling it from the bottom and not only to hit the fire button. So this makes it feel like its a leave at home unit to casually smoke while your on the computer or watching TV. Because of the awkward heavy it feels like it could slip out from your hands if your hanging out with your "compadres" or taking a hit while walking with it.
The mouthpiece spits back if you don't allow it enough time to saturate the e-juice into the cotton.. However, I have also gotten plenty of dry hits from it because sometimes you just have to be bold enough to give it a good strong pull and allow it to spit back at you to actually pull the juice back into the cotton..
And the cartridges are magnetic so count on having accidents in your pockets if your actually putting this in your pant pockets.
Also the battery doesn't last as long as you would want it to.. If your a hardcore smoker the most you will get is about about 2 or 3 hours.. Then you would have to charge it again..
I would say when all these hurdles have been defeated the unit works smoothly and really well. But you don't want to have all these arguments with your e-cig.. lol.
If anyone does consider buying one I bought some Naked brand e-juice and their ratio works well on the unit.. They usually have their ratios right on the front of their labels. So I would start there as far as ratios go if your planning on using it with your DIY juice..
To be honest I bought this unit to test out illegal substances that I could blend with e-liquids since it doesn't have any coils or ceramics to ruin anything..
So far the cotton seems to filter things pretty well..
I dunno how open this community feels about such things so I am not going to be so bold since I just joined this forum.. lol
I would say if you like the design of this unit..
I would recommend getting
The Aster 75w By Eleaf which bears a similar square laser cut design but looks much easier to hold and walk around with.. Its not an ultrasonic device but it is pocket friendly..
I got my Rhythm from MyVaporStore for $47.
They have 10% off coupon codes if you search google.
USONICIG Rhythm UltraSonic Starter Kit
Additional Cratridges from MyFreedomSmokes for $5.95
Ryhthm Ultrasonic Replacement Cartridge 2ml