Posting his impressions on Facebook after a set visit, the comic writer praised lead actors Karl Urban and Olivia Thirlby.
"Very pleased with what I saw of Karl Urban and Olivia Thirlby," he wrote. "Both excellent in their roles and work well as a team. Entire crew really dedicated and determined to produce a damned good movie."
Wagner went on to commend the film's use of 3D and detail his discussions with screenwriter Alex Garland. "[We] had our disagreements but he has usually had a convincing argument for doing things his way," he added.
"On the main issue, concentrating the plot on a slice of life rather than trying to convey the wh… ole sweep of Dredd and Mega-City life, I now see that he's right. It was one of the flaws of the first movie, they tried to do too much."
Directed by Pete Travis, Dredd arrives in theatres in December.