Ok, I have one of these. Ergonomically, it feels slightly heavy for a female hand, but I am getting used to it. The button seems stiffer than a standard ego button also. I don't notice it if I am vaping right handed, but I do if it is in my left (I am right handed). I also like, and this is silly I know, the fact that it is really easy to set down on the desk without it falling over. Stands up beautifully.
Fits all my ego atomizers/clearomizers and looks nice. If a little fat.
I don't know how long the battery will last as I have only used it 2 days, and I switch out units filled with different flavors often. However, I am a chain-vaper so 2 days is pretty great. No loss of vapor in 2 days so far.
I like the fact that I can replace the batteries inexpensively, and that I can pop it on the same ego chargers I have.
That's my non-technical review