Yup, you're right. More nutritional research is need and consumer availability is uncertain.
Further reading at the end of the Wiki article:
"Critics of genetically engineered crops have raised various concerns. One of these is that golden rice originally did not have sufficient vitamin A. This problem was solved by the development of new strains of rice. However, there are still doubts about the speed at which vitamin A degrades once the plant is harvested, and how much would remain after cooking. A 2009 study of boiled golden rice fed to volunteers concluded that golden rice is effectively converted into vitamin A in humans.
Greenpeace opposes the release of any genetically modified organisms into the environment, and is concerned that golden rice is a Pandora's Box that will open the door to more widespread use of GMOs.
Vandana Shiva, an Indian anti-GMO activist, argued the problem was not that the crop had any particular deficiencies, but that there were potential problems with poverty and loss of biodiversity in food crops. These problems are aggravated by the corporate control of agriculture based on genetically modified foods. By focusing on a narrow problem (vitamin A deficiency), Shiva argued, the golden rice proponents were obscuring the larger issue of a lack of broad availability of diverse and nutritionally adequate sources of food. Other groups have argued a varied diet containing foods rich in beta carotene such as sweet potato, leafy green vegetables and fruit would provide children with sufficient vitamin A.
Because of lacking real-world studies and uncertainty about how many people will use golden rice, WHO malnutrition expert Francesco Branca concludes "giving out supplements, fortifying existing foods with vitamin A, and teaching people to grow carrots or certain leafy vegetables are, for now, more promising ways to fight the problem."