Working or volunteering in the human services field can be rewarding if you're trying to make a difference in the lives of others. Working or volunteering at nursing homes is no different. However, some people I know have wondered how you can make a difference in the lives of nursing home residents since they're at the final stages in their lives. My response to that is some nursing home residents aren't there for a short time. Some of them are there for a year or two...and it some cases, much more than that.
That's a little bit like thinking that, once you're over insert age at which one becomes old it's pointless having a (let's say) hip replacement, because you won't get many years use of it. Some 70-year olds will get 20 years use out of it, some 40-year olds will die tomorrow (recently read about a girl of 15 having a heart attack and dying). ANYTHING that you can do to improve the quality of life of ANYBODY (nursing home or nursery) helps the overall human experience.