I own 2 town homes which I have rented out for 25 years, so they are both paid off and are generating significant cash flow for me and my DW (I am semi-retired).
I avoid the headaches of being a landlord by employing a management company - they take 6.5% of the gross rent. For the first 5yrs, I managed the properties, but grew tired of it, and by then the rents had increased enough that I was able to justify a management company. For me, it's definitely worth paying someone to manage collecting rent, maintenance, and all tenant communications.
Now that the mortgages are retired, my expenses are property taxes, HOA, and occasional maintenance costs - in addition to the property management fee.
If you can swing it, having passive rental income to augment investment income in retirement is great.
It took me 25 years to get there and am glad for the effort. Just have realistic expectations for the near term (say first 10 years).