I only have the free version, and I've only played 12 games, but in those 12 times I've lost all but 2 of the matches -- and those losses weren't close by any means. I realize that dice results are randomized (like in the real world), such that one could really have such bad luck to consistently roll poorly, but when I'm not touching the physical dice myself, it feels like there's more at work than simply the arbitrary nature of dice themselves :-/.
The zombie players seemed to always run by the rule of "roll until you get two shotgun blasts", and that worked well; not only did they usually get the small gains (1-3 brains), but they also got the huge gains (5-8 brains) too often. I, on the other hand, tried to also observe the "roll until you get two shotgun blasts" rule and suffered for it. More times than not, I would have a single shotgun blast, think that it's safe to roll again and immediately get 2 more blasts. And then, of course, there were the lovely times of rolling well to start with 2 or 3 brains and then immediately getting a roll with 3 blasts.
Now, in all fairness, if I would sit down and play many more games perhaps the win/loss ratio would begin to even out, but this heavily skewed beginning leaves me completely disinclined to attempt that stretch goal. This is the first time I've encountered an iOS game where I even began to consider the possibility of weighted dice … and consequently I probably won't be picking it up again :-(.