My husband has been on Risperidone since 2011. He was put on it because of the horrific hallucinations & paranoid delusions he was suffering from. He was literally living in a 24 hour nightmare from which neither he nor we could escape. His consultant was reluctant to use anti-psychotics because of the risks, but eventually had exhausted all other avenues, and felt that William was also under significant risk because of the stress he was under - and that things were becoming very dangerous for us because of his delusions.
Starting him on the Risperidone was like flipping a switch to turn off the paranoia and hallucinations. No more hearing voices screaming at him, no more seeing evil children in the trees throwing things at him, no more "men" living in the house/garden/attic etc. The consultant tried a few times to reduce the dose, but each time the hallucinations came straight back. Thankfully, William has suffered no ill-effects from the drug.
As with all medications, the list of side effects given are for the side effects that people may suffer. Not everyone does. But like all medications, you have to weight up the pros and cons. For us, the risks of the possible side effects were well worth it for the quality of life it gave William. It meant that he had two good years at home, when he was happy and contented, before the natural progression of his dementia meant he needed more care than I could give him on my own, and he entered full time care in September.