Got mine today... still testing but so far I like it. Nice draw, great flavor.
A few tips - as Vicki said when unscrewing the base (bottom), there is the "atomizer head cap" that can also unscrew - so when you start to unscrew the whole bottom base, give it a little tug after clearing the threading so the head cap comes with it, other wise the head cap will be in the 'tank' part which, if it happens you'll have to grab it as well, then screw it back into the 'base' bottom part.
Another thing. The manual says to fill - "remove mouthpiece and fill in the hole" in the 'well'...
don't do this. lol... Fill from the bottom as it says here at joyetech:
Joyetech eGo-CC Atomizer (Changeable clearomizer)
...scroll down where it says 'Add liquid from the bottom'

There is a hole and if you have some thin tip bottles exclusively from Vicki

... you can get it in the hole but filling from the side can work as well..... just don't try filling from the mouthpiece - which I did at first
The tank is stainless steel with a window that is either glass or some polyxxx and it is flush with the tank. I had mine on a Twist set to just above 4 V and there is quite a bit of conduction so it can get hot around the base of the cc. I had a lighter flavor so I dialed it down to about 3.6V which is fine. It appears 'long' in length but it's just a hair longer than the T3's. I didn't check the capacity of the tank - I'm guessing 2.0ml but that's a guess.
Mine came with a atty head with 3 slots - which means it's an "A type" head....
http://www.e-cigarette-forum.com/forum/ego-type-models/315116-type-type-b.html#post6690249
.... but I'm guessing the B type heads will work just as well - maybe a bit less wicking, tighter draw perhaps.
There's been no leaking or gurgling and the airflow holes by the mouthpiece looks like a good solution. It appears that the 'well' (when you remove the mouthpiece) can get a bit wet but the orings on the mouthpiece will prevent any juice in the mouth. So far none for me.
I'm rather impressed and I've been a Tabac BCC user without leaks or juice in the mouth for quite a while. I'm thinking I can now use the stockpile of A and B heads I have with this cc clearo!
addition:
There is some gurgling at the very end - time to refill.....