Mortality and injustice (natural and human) are the only things that trouble me about the absence of God.
Because there is no wise and compassionate overseer to battle and suppress injustice, the world is full of it, and humanity must struggle on its own to rectify this defect. But humanity lacks the wisdom and powers of a god, so it realizes justice imperfectly and incompletely and only at great cost. We evolve our society into a better state so slowly most of us will never live to see the better world we strive to create and leave behind for those who will succeed us. We battle crime and disease and corruption and tsunamis and ignorance and insanity and every natural and human injustice, and we would all be rid of these things at once if we could, and the world would be wonderful without them.
The greatest benefit of a world with a god in it would be that none of this would plague us. That it does plague us proves this world has no god in it. Eventually, we will be able to create our own worlds, and through trial and error we will create on our own the better world that a god would have created in the first place, had there ever been a god. But that is still a long way off. In the meantime, we continue slowly building a better world out of the one we're in, so that each generation leaves a world behind that is at least a little better than the one before it.
Unique among these evils is death. Which is unique because of its finality, thoroughness, and irreversibility. It is annoying that I will cease to exist in a few decades. I still don't lose any sleep over this, since after I'm dead I won't be around to worry about it, and when I'm around, I'm not dead, and thus have nothing to worry about. I enjoy the life I have precisely because it is all I will get. But I would very much have liked to live a great deal longer, to accomplish and experience a thousand things I so much wish to, but know I'll never have time for. Through technology we will defeat death ourselves eventually, and although I'm not likely to live long enough to be among those who enjoy that triumph, I am very happy for those who will. But once again, a world with a god in it would not have death in it to begin with.
Though these things trouble me, they trouble me only because I know they are true. Accepting reality for what it is, instead of hiding from it in delusions of magical salvation and eternal life, is fundamentally required of anyone who intends to actually make the world a better place, and their own lives better. The sooner you acknowledge the defects of the world, the sooner you will be motivated to roll up your sleeves and get to work fixing it, while making the best of what you have.