I don't believe his credibility will be tarnished. The reality is Abrams has been a very successful director in spite of some of the mediocre products he has been responsible for. Star Trek Into Darkness comes to mind immediately as being an example of a completely lackluster effort that should have knocked him down several thousand pegs. It's scary that he went from Into Darkness to Episode VII. However, yes because he is an uber-fan of Star Wars hopefully this will be his greatest film as well as a wonderful Star Wars movie. The only reason I disagree about the argument of him being a fan playing a big role in him taking on the movie as director is because Abrams himself used that as one of the main reasons why he didn't want to helm the film. It is not like he was not aware that The Force Awakens would make a "shit ton" of money when he was initially offered the job. He knew Disney wanted him and therefore was in a position to get whatever piece of the pie he felt he deserved.