I find it very meaningful work. I have done some work with elder abuse, and as a result have done some long-term counseling with elderly clients. A couple of reasons I enjoy it:
For some reason the engagement is different - it's more human, and more philosophical. I learn a lot more during the engagement - not just about my client, but about the world and what they've experienced.
Keep in mind that the elderly have lived an entire life - that is, you will be dealing with issues such as childhood trauma, adolescent trauma, substance abuse (past or present) IN ADDITION to all the issues related to aging. If you've lived 80 years, chances are you've touched on just about every issue social work deals with, from the DSM to major policy/systemic issues like racism or sexism.
You learn some really cool things. Chances are, you'll be about 20-50 years younger than your client. Their views on mental health, politics, religion, you name it - are often layered with history that can be really fascinating. (I'm not ashamed to admit that a few therapy sessions have been a bit derailed by a story of my client's that catches my interest).
It challenges your boundaries in an interesting way. What is the true meaning of a "treatment plan" or a "presenting problem" if a natural death is imminent? What does it mean to meet for an hour of someone's time if they have limited hours left? I find myself often chatting with clients about leaving a legacy, finding meaning in pain or in life, and it brings up some fascinating and invaluable counter-transference. I don't always leave my work at the office, yet I often am grateful for how the work changes me.
It's where the $$$ is going to be as the baby boomers age ;)