Briefly, my grudge against God is this: if you gave us a moral compass, you should have taken more care to align it with yours, otherwise it makes no sense to many of us. This universe seems quite compatible with a malignant God or with an indifferent one. But my ideas of goodness seem much more generous than those of this particular God.
Do not take me wrong, I do think this world to be a marvel, albeit a terrible one. Is it better than nothing? It certainly is, for me, but I bet there have been countless millions that would have settled for nothing instead. Yes, we have the promise, but I do not trust the party who made it.