Earlier quoted context omitted.
I'm British and to me "quite" here means "mostly" i.e. not entirely. Could well be a misunderstanding but it should be made clearer as this data is priceless.
Doesn't "quite good" mean "great"? That was my impression, at least.
It's fine in a spoken context as tone can add sufficient extra meaning. If you can guarantee the listener is expecting an informal register then it probably also comes across as a superlative. "I met him and he's quite unpleasant" would usually imply he was a total c*nt.