I have looked at Berlin houses online before as well. I was, of course, tempted by the asking prices for both singles or multis. But, I also worried about why are the home prices so low? When I looked into it, like @Brett C. was saying, appreciation potential appears minimal; even more so than most places in the slow growing and aging state of New Hampshire. The Berlin population looks like it peaked in 1930 and has more-or-less been dropping ever since (https://en.wikipedia.org/wiki/Berlin,_New_Hampshire). Many of the biggest employers are various forms of the government and average income is relatively low for NH (https://www.nhes.nh.gov/elmi/products/cp/profiles-htm/berlin.htm) - telling me there are few good jobs for ambitious young people who could fill your rental.
But, if you are OK with risking flat-line/depreciation in housing values in exchange for decent cash-flow prospects it may be a good choice.
Although, I imagine that an important detail to find out is how easily homes rent in the area. Is there a lot of vacancy or is it hard to find renters that can afford to keep making payments on time in Berlin, NH? Myself, I don't know.