Just got one last week. Really only one "complaint" about it, and it's not a big deal. You do have to take the tank and base off the 510 connection part to adjust the air flow - a ring around the internal connection. So initial setup can be a bit tedious, but once you have the air flow set to your liking, you're not changing it anyway.
Easy as a KF to build, and gives the option to use the hole or wind around the screw, like the 3.1 model KFs.
Air flow can be adjusted from a nice stiff draw to inhaling through a straw that's in dry air. 4 holes in the base for intake, which is plenty. Not sure if drilling them out would make a difference, even at the wide open point.
And since the bottom is, effectively a double bottom, it's sealed at the battery end, so no chance of drips or leaks to the battery.
Pyrex tube is a plus for some, although not critical for me.
And does come with a silicone ring that you can use instead of the fill screw, which plugs the fill hole. So no screwdriver needed - and it works!
It IS lighter than the KF lineup unless you're using the tall poly tube - and then maybe still a bit lighter. (That said, one of my KFs has been set up with the poly insides and tall tube, and on an aluminum Tesla VV/VW the whole things about the same weight as a 1300 Spinner and Protank!)
Would I consider adding another to my collection? Nah, not unless I had another bout of shinyitis!
It also holds a bit more than the KF, so I guess I'd have to say somethiing like "vapes great, less filling"