One major advantage of the adult stem cells is that they are not prone to rejection when used in transplant procedures, while the rate of rejection in embryonic stem cells is not yet well determined.
Other major advantage of stem cells is that they are pluripotent cells, mostly embryonic stem cells, and they can produce most of the type cells.
Though there exists no standardized technology to produce large amounts of stem cells in culture, the embryonic stem cells can grow more than 1 year in culture.
The stem cells are appreciated for their unequaled regenerative properties and they are mainly used to treat disorders like diabetes or heart diseases. The adult stem cells, which are collected from bone marrow or peripheral blood, are mainly used to treat lymphoma or leukemia.
The embryonic stem cells could be of great use in treating heart diseases, diabetes, muscular dystrophy,vision and hearing loss or spinal cord damages.
Stem cells are not a matter of pros and cons; they are necissary for multicellular life.
They are necissary because they are the reserve supply of "blank" cells for use in the body. If a cell is damaged beyond repair, a stem cell has the ability to activate the gene set specific to that cell type and adopt that cell's functions.