Very very first impression:
Form factor:
No two ways about it: it's cute - it's downright adorable.

I really like the combination of this batt and this carto aesthetically. It's sleek, the color (I got the red) is very nice, it has depth and texture to it. And it's not tubular. The downside is that I held other cartos against it to see how it would look, and it looks silly. LOL So it has to be this particular carto, or one with the same shape, with this batt - for me, anyways.
The feel:
As everyone has said, it's small. It's just on the verge of being too small for me, and I don't have very large hands. But that could be an advantage, too, if you want to hide it.

The oval shape feels very good. Really like that. And finish on the batt is very nice on the skin too - it's not rubberised, but the feel is similar, both silky and non-slip at the same time. The battery is very light - not sure whether that's bad or good. On one hand, it won't stretch out your pocket, on the other it's doesn't feel very solid... It certainly won't tire my hand out.

I like the button, it feels good under my finger, the positioning is good, and it's clicky.
The mouthpiece of the carto feels good to me, I like whistle-tips, but it does get a bit hot.
Functionality:
Can't say much about the batt yet. I don't think it's regulated, it seems to be giving a bit less power with time, but not too bad. The charging thingie has got to go though. I am not even sure how to set it up once the batt runs out of juice.
There are good and bad points about the carto.
The good is that it vapes quite well. No dry hits in sight. Good vapor and flavor. Maybe a slight off taste - either from wick/filler in the center stem, or something else, but in general, even for a flavor nazi like myself it's very usable. It may get better, too, I'm only half way through the first tank. So that's quite impressive, I'd have nothing against using this carto on regular basis, and I'm extremely picky.
The not-so-good is the construction quality. Both of the ones I got have a crooked stem, so it ends up either not sealed well, or the mouthpiece ends up crooked. The tube is glued to the base (don't like that to begin with), and the glue is not neat at all. The plastic is quite thin. I don't see how it can be reasonably cleaned. Once wet, it won't dry for days and days, and there is no way to tell if it is, in fact, dry. Which makes it pretty much disposable. Considering how no other carto will look reasonably good on this batt, either the quality of this one has to improve, or the price has to be pretty low for it to compensate. I wish it had a lid, too - that would make it much more pocketable for me. I don't like naked cartos in my pocket.
All-in-all, I like it quite a lot, both in looks and functionality - but with a caveat that it's a "light" quality unit, and, I think, needs to be priced accordingly. Just IMHO. I think it can go out into the wild, though.
Hey - any more colors in the offing? How about purple?
Speaking of colors - ladies, you have
got to get the pink Twist, it's soooooo pretty. And the white one is very nice too. Thanks for ordering these, guys! Love them.