If you want a great overview, I suggest you read it. If you want the key point here it is:
“Bang¬la¬desh, where Gram¬een Bank was born, is still a desperately poor country. The more modest truth is that microcredit may help some people, perhaps earning $2 a day, to earn something like $2.50 a day. That may not sound dramatic, but when you are earning $2 a day it is a big step forward. And progress is not the natural state of humankind; microcredit is important even when it does nothing more than stave off ¬decline.”
Development economics is difficult there is no easy answer, but yes microcredit is helping, but it is just one of many things that needs to be done.