I don't think TPGW's author is necessarily trying to make us sympathize with Teppei, specially after this week's chapter. Even though his situation is difficult and he's making it worse at each action he takes, he's already becoming a nuisance to other people. I don't sympathize with him, and that doesn't make the series less interesting to me.
I understand people who are not liking the series because of Teppei's character, but I don't think this is a demerit to the series. I want to know how he'll handle, solve or worsen the situation, and that makes me want to keep following it. I also think Aino becoming his assistant is interesting and brings a lot of potential situations.
I know that the first chapters are the most important for a new series, as it have to get the attention of a group, but maybe the focus of the series is not the time machine or whatever, but Teppei making mistakes and having to deal with it. His first ordeal was to deal with his own guilty (and he's failing miserably), I believe he'll have to deal with with other people very soon. And that's where I think the author have to really nail it, because if the conflict only stay inside Teppei's head, the series will get stale and go nowhere.