I handled one at the gun show a week ago. The grip felt really crowded and short, much more so than a Kahr PM9. Overall, the gun just felt very uncomfortable in my hand. The shape of it was not ergonomic at all.
I think it is due to the fact that the Beretta has it's trigger mechanism above the trigger which pushes the trigger down further away from the slide. A Kahr has the trigger mechanism offset from the trigger in some way that keeps the trigger much higher up toward the slide. The end result is that the Kahr has more grip to hold onto, and feels much more ergonomic than the Beretta.
I would pick the Kahr over the nano on the feel alone, regardless of how reliable the Beretta ends up being. The Kahr is smaller, lighter, and better designed for the human hand. It looks like an experienced company like Beretta, who has waited so long to get into the subcompact 9mm game, would at least try to one-up the competition, but the Nano is NOT a step forward in my opinion.