The inability to choose one's true love for a spouse; the inability to choose one's profession freely; the inability to come and go freely; and the inability to speak one's mind freely are just a few of the drawbacks of Jonas's world.
The most salient effect of the community of Jonas is the dehumanizing of the people. Teens take a pill to deaden the erotic urges natural to people; the children are compartimentalized with numbers; they are given bicycles at a certain age, their hair is worn in a uniform style at certain ages, and life vocations are chosen for them by the higher authorities. Clearly, there is no development of individuality.
You say "so far," which implies that we're only supposed to address it up to a certain point in the book. What point is that?
For me, the most negative aspect of Jonas's community that we see relatively early on is the lack of any true emotional connections. The members of "families" do not really love one another. They are sort of just together for convenience. This sort of lack of love and other emotions seems like a major negative to me.