For some reason, this isn't a very popular drug and tends not to be used. I reviewed the literature on this several years ago to present to medical residents. I was surprised to find as many positive studies as I did and few to any negative studies. It is a drug which should be tried if there are no other reversible causes of dementia. Don't expect major improvements.
Side effects are remarkably rare and is basically a previous reaction to the drug.
However, controlled studies have not demonstrated effectiveness. My mother has recently been diagnosed with alzheimers, and has been placed in a 24-hour care facility. Alzheimers Dementia is commonly associated with levels of agitation and disorientation. Many studies have demonstrated that a closely supportive environment which maximized sensory input and one on one caretaking will reduce this agitation and disorientation significantly. However, most nursing facilites lack the financial and personal resources necessary to provide and maintain this level of care.