Ask HN: New job at startup. I am overwhelmed. Is this normal?

I started a new ruby remote developer job in a startup. The money is good and it looked like a tech challenge. However, since a month ago (when I started), I am totally unhappy. The goals are impossible to reach, which means working extra hours or weekends, and the organizations is terrible. You can work on your task because you depend of a colleague to finish his task first. The documentation is pretty bad too, so I have to keep asking my colleagues about new parts of code I have to work.

Is this normal? Or is this specific startup that is making my life miserable?