Generally, I'm impressed with the overall design. It feels nice in your hand and the filling is very easy. However , unless I have a dodgy one, the squonking action let's it down. Whether it's because the juice has to go up, across and then up again through the 510 I don't know but the rate or pressure at which the juice flows to the rda is a bit lacking. When the bottle is full , it's fine, but as it drains to about the window and below the rate at which the juice flows diminishes and it seems to blow bubbles slightly . I don't think there can be a leak anywhere because there is absolutely no juice escaping.
Compared to my vt inbox in that respect, it's lacking .