My problem with Jintan is that, as the protagonist, he most likely won't end up changing like the other characters will until the end of the series. Hopefully, the series does a good job of having his change be gradual instead of a more-or-less sudden realization.
For example, he was enjoying himself playing Nokemon and
Those types of things are what I'm hoping to see peppered throughout the series.
What I find interesting is that he rejects everything. Everything that seems like it would hurt him, he says doesn't affect him and doesn't interest him. It's obvious why, but if he keeps that attitude up, it'll be really hard to bond with the other characters. I hope Menma and the other characters don't have to do everything for him.