Answer:
The generally agreed upon positive affects are listed within the IPCC report. The validity of the concept of man induced global warming is not part of this question so it is ignored.
Increased CO2 is considered to be a beneficial attribute of global warming. Additionally, longer growing seasons and more water vapor are possible which would in turn cause increased crop production and more tillable land.
Increased heating could also cause reduction in the need of fuels for warming homes and businesses.
Finally, there is mixed reviews on the number and intensity of storms. Major hurricanes (level 5) have been decreasing in number. Some experts believe this is due to a decreased delta between sea temps and air temps. It is the difference of temperature between the air and the water that causes severe weather.