It is a bit on the sour / tart side of yogurt flavor. (homemademommy.net)
I don't love things that are too sweet, but I just felt like it was a little on the very tart side and needed something to cut it; however, it could have been the apples, so next time I make it, I will taste the filling once cooked and add additional sugar as needed to ensure the ratio is accurate. (browneyedbaker.com)
i like my yogurt on the tart side, so i've only added a teensy bit of honey, but you can certainly add more if you please. (mynameisyeh.com)