 
The vaping Gods smiled down on me this morning!  My GX2/4 is in hand and in use!  Still very early, but my first impressions:
This thing looks awesome in the blue I waited for!  It seems even smaller in dual battery configuration then the Alien in hand, but I set it up in quad mode to start.  I was concerned with the size and weight for my wonky hands.  The fit is surprisingly comfortable and the fire bar makes firing effortless, just a squeeze.  I was surprised by the seemingly lack of heft, so compared its weight to the G-Priv 220.  Obviously heavier, but the G-Priv came in about 304 grams and the GX2/4 in quad mode at 396 grams (weights with batteries, no tanks).  Heavier, but the extra battery life and more comfortable fit give the edge to the GX2/4, IMHO.
Menu system is the same as the Alien and AL85, but I like that.  Too early to judge firing consistency, but really nice with the first tank I am using (not the BBB it came with).  I am trying some Samsung 30Q's for the first time and anxious to see how long it will run in quad mode with the varying wattages I vape.  Since I don't use TC, I will leave that to others.
Only thing I noticed so far that could be of concern is the battery ribbon in the mod part seemed a bit short.  It is not long enough to go under both batteries.  But it does seem the "outer" battery has enough opening to easily remove the battery without it.  Perhaps 
@Mike McVape will comment on what his is like for comparison.
All in all, this mod just might be my do everything mod....besides being my work mod I can beat around with.  I could easily see putting away 10 of my other 11 mods (keeping a work mod 

).  With what is surly excellent battery life and the ability to swap to a pair of married batteries while charging the 4, not much need for anything else except for back-up for insurance.
It is well worth a look and I wouldn't be surprised to see this thing really take off in sales!  It is the best do everything mod I have,