It will make a fortune because the target audience and Bronies will go to to see it several times; marketing's a no-brainer, seeing as how social media'll take care of that. Reviews ... I expect it'll be critically-panned as kiddy-fare, but the fans'll enjoy it.
Sometimes, I don't know; most of the people are great, don't get me wrong, but those few jerks (especially the jerks which are well-respected for unfathomable reasons and tend to control MLP-related websites) really rub me up the wrong way. There's always elitism, even here.