You're holding them wrong. Seriously, what do you mean by 'goes flat'? The bottom wears off? Or battery? Just get a charger, not a big deal. Also, I can't find a position where it nips my fingers. Bottom doesn't fall of if you close it properly. I haven't had any of such problems with Magic Mouse, although I miss the middle button. Scrolling in both directions is much better than any other mouse.
Batteries. I bought a charger and Sanyo Eneloops (low self discharge). Life is terrible. Stick your fingers on the side and press the top down - ouch. Bottom does fall off mine even when closed "properly".
I think the crucial part is how you hold it. I suspect most people dislike the Magic Mouse because they hold it like a regular mouse. The way I hold it, on the other hand, is with a 'cupped' hand where my thumb and ring finger clasp the mouse and move it, my palm hovers pretty high above the mouse, and my index finger scrolls from slightly above the center of the mouse surface.
I'm not sure whether it's bad design that you 'should' hold it differently, but at least for me this is why I quite like the mouse.
(the bottom has started coming off though. that does bother me)
