Pros of GMOs: Adding additional vitamins and minerals to aid ailing populations and help with overall health; Creating plants that assist farmers to combat soil erosion; and GMOs allow us to create more crops to feed the worlds fast growing population.
Cons of GMOs: GMOs could cause people with certain allergies to have their allergies triggered (ex: a peanut gene put into another organism); Small farmers can't compete in the market with large farmers using GMO products because the cost is too expensive for them; and there's no testing to determine the long term effects of GMOs on humans.
In my opinion, GMOs are a good thing overall. GMOs give us more food, more vitamin-rich food, and they help to prevent soil erosion. With continued testing and experimentation, we should resolve any concerns over health risks. Assistance could be given to the smaller farmers, so they can compete with the larger farmers with GMOs.