It's always hard to say how someone will behave after the children come, because you will have stress on you as never before. I think a lot of men regret having children, especially once their wife is preoccupied with the baby and no longer catering to him as much.
With my son in law there were a lot of red flags, like his parents (both mom and dad) are physically abusive and see no issue with it. Even now, he's 28 and sister is 24 and the cops are called on them regularly. Last time it was because the dad was strangling his sister.
He never loved my daughter. She sees that now. We saw it before. But she has pretty low self esteem, so when he paid attention to her (looking for sex), she felt special and just went with it.
Did I assume he'd be a terrible partner? Not at first. He stutters and presented himself as shy and respectful. After the kids came he became entitled and abusive to both my daughter and the kids. She doesn't leave him alone with them and he visits them only at our house. In addition, she doesn't divorce him so that he doesn't have custody rights. So far he's been good with it. He comes and goes as he pleases, so everyone is as happy as we can be given the circumstances.
That's probably more than you wanted to know, but the short answer is - no - at first I thought he was a really sweet kid.