First things first, if you want to avail of rent-a-room relief, make sure you rent for at least consecutive 28 days.
We did it once, with two students for 3 months, had no major issues. They were respectful, cleaned up and were generally easy to have. All that being said, what we had underestimated was how much we valued having the the space at home to ourselves. We didn't feel totally relaxed while they were in the house, and we breathed a sign of collective relief once they had left. To each and everyone their own of course.
I'd recommend if you do it that you put a set of rules together, so that everyone is on the same page (visitors, smoking, what happens if you damage something, cleaning etc).