I looked it up and this was the first result
https://pdfs.semanticscholar.org/c911/5ad056fc1bb4f257fa6109...
http://www.goldenrice.org/PDFs/Dubock-The_present_status_of_...
> "In conclusion, each of the studies discussed regarding the effectiveness of golden rice concluded that it was indeed effective at providing vitamin A. "
Stone and Glover are saying that the current studies which prove Vitamin A are effective aren't comprehensive enough. However as far as I can tell all the research so far points to golden rice being effective.
Stone and Glover later wrote: "IRRI’s own assessment that the rice may augment the already successful nutrition and breastfeeding programs, at least in
some ‘‘difficult to reach’’ areas, is plausible."
Sound like they are critical of it for many reasons but accept it working as a possibility.
https://pages.wustl.edu/files/pages/imce/stone/stone_glover_...