Gunn has literally never made a bad film, they've all been hits and I firmly believe this will be his biggest film. Fears about it seem almost like he is some first time director and not successful. Man of Steel I was afraid for because Snyder had had flop after flop following 300. I was absolutely shocked when the guy who directed Sucker Punch was picked to direct Superman and I generally liked his movies to that point, especially Watchmen. When I saw MoS in theaters I spent the better part of the next decade convincing myself it was a great movie and only in the last few years, in spite of seeing the flaws, have I conceded to myself that it is "ok" as a dark elseworlds Superman story.
Everything coming out of Superman so far indicates a deep love for the DCU, especially the post Crisis era when DC was firing on all cylinders and the better elements of the silver age. It feels timeless.