So far this appears to based on the framework of a fairly standard type of fantasy harem manga. The size difference is a nice twist, but it appears to be basically cosmetic, as the MC doesn't appear to be at any real disadvantage because of his "abnormality". It's only two issues in at this point, so it is a little early to tell the ultimate quality of this thing. Will it break new ground? Will it devolve into over-familiar tropes? Will there be any real plot, or is this just endless slice-of-life? Will it take advantage of its novel setting to go beyond what the framework dictates?
Time will tell (assuming this isn't axed in the next half dozen chapters). So far, it is neither bad nor great, clocking in on the good side of competent. It has the potential to be something exceptional, but I have been burned too often by great potential and/or Japan's fickle audience to hold out much hope.
One criticism I can make at this juncture is inconsistent scale in the artwork. The MC does not seem to have any fixed height relative to the other characters, going from being small to ridiculously tiny from one panel to the next. I realize from the stylized nature of the artist's work that we should be assuming a bit of cartoonish flexibility to assist in the humor, but the disparity is occasionally so large that it disrupts the suspension of disbelief. Hopefully as the artist gets used to the characters, this will firm up some.