The good news is that reportedly the film got rave reviews from the people who watched the movie. According to El Mayimbe, "It went through the roof. It was awesome. It’s the superhero movie to beat this summer.”
Even though it's unconfirmed if there was a screening, it's usually pretty standard practice for studios to hold early screenings of their movies for friends and family. In fact, Warner Bros. did an early screening for The Dark Knight Rises, which resulted in early reviews leaking out on Twitter. Of course, considering that early screenings do often consist of employees and people with a vested interest in the success of the movie, reaction is usually positive. The early screening of The Dark Knight Rises got a standing ovation.
However, we're betting that the Man of Steel is the real deal. The Man of Steel trailers look incredible, and the cast and crew have been saying all the right things. Director Zack Snyder proved he could make movie magic with 300, and it looks like after a misstep with Sucker Punch that he might have recaptured his former glory with Man of Steel.