The film was, in the words of Scorsese's mentor, John Cassavetes, "a piece of shit," but it put the young director on the map. After Boxcar Bertha, Scorsese asked Corman to produce his next film, but Corman would only do it if all the characters were black people so they could pass it off as a blaxploitation film.
Scorsese declined the offer and made the movie without Corman and on a smaller budget. The film was Mean Streets, the first "real" Scorsese movie, with all the usual elements like Italian people, violence and Italian people getting violent.
The artist hadn't yet entered his "oranges fucking everywhere" period.
Mean Streets paved the way for the rest of Scorsese's career, but none of that could have happened without Corman. See, this is the magic of Corman's "Make it cheap and get that shit out the door" assembly line approach to filmmaking. Why not throw a talented kid at the helm of the project? What did he have to lose? It's a chance Scorcese might not have gotten elsewhere, and that crash course in movie making taught him everything he needed to know about getting movies done fast and under budget. You can bet that came in handy when he was directing Taxi Driver for $1.3 million.
Totally worth it, despite being forced to live off of his own fingernail clippings.