Absolutely, especially if it's in the first chapter. Any grammatical error or typo in the first chapter is an instant drop for me. If the author couldn't put in the effort to proofread the first thing their readers will see, why should I put in the effort to read it at all?
Other than that, I can excuse the occasional typo or grammatical error every once in a while. It's not that big of a deal. Hell, even professional level productions make these mistakes sometimes.
But if it's to the point where lines don't make sense and it's a pain just to follow what's going on, then I won't bother. I understand that a lot of the people who write these kinds of things are ESL. But again, if they aren't bothered to learn the language they're writing in, why should I be bothered to decipher what they tried to write?
IMO they'd be better off writing in their mother tongue. There's nothing wrong with writing something in a language other than English.