He married her when she was 9 and he was 53. He didn't consummate the marriage until she was 13 or 14.
http://www.wikiislam.com/wiki/Aisha's_Age_of_Consummation
http://www.muhammadanism.org/Hadith/Topics/Marriage.htm
Second one's an article about how that move of his set the stage for Islam men to do the same thing.
As an event it does have to be seen in its context of time and place. The custom of taking child brides existed before Mohammed. And some texts place the promising of Mary to Joseph in marriage at the age of 9 and the birth of her first child at 12. And in the chapter of Numbers in the bible there is this
"Now therefore, kill every male among the little ones, and kill every woman that has known a man by sleeping with him. But all the young girls who have not known a man by sleeping with him, keep alive for yourselves"Kids were dashed against rocks for revenge, captured into slavery, eaten alive by bears sent by god (allegedly), slaughtered as pawns in political games such as the murder of all firstborn sons. Aisha from what is supposed to be her writing appears to have loved Mohammed. In comparison to the bloody deaths and miserable lives of a lot of children, it could be argued she had it easy.
Life expectancy obviously does play its part but in the end shouting nuance at religious figures is pretty much missing the point which is that all religious texts carry the social norms of their time.
Now here's a pedo for ya, not just a pedo, ...but an incestuous one at that.

Jerry Lee Lewis married HIS COUSIN Myra when she was 13. Great balls of fire indeed.

Here they are, keeping it in the family.
What's more, ...apparently at the time of William Wallace Braveheart's death the french princess he was riding was only 4 yrs old. Well it's on the
Stewart Lee dvd part 1 anyway. "That would have made William Wallace Braveheart, scotland's national hero, a paedophile. A scottish paedophile; the worst kind".
You don't want to know what he says in
part 2