According to Rotten Tomatoes' Man of Steel review page, the film has garnered 70% by "All Critics" while the "Top Critics" has garnered 54% so far.
The film's consensus has said the following: "(Man of Steel) provides enough exhilarating action and spectacle to overcome its occasional detours into generic blockbuster territory."
Now this doesn't necessarily mean much but I follow this site daily and usually when it reaches a high percentage level it only continues to decline to a certain extent. But that also doesn't mean the film's rating can't rise.
Only time will tell in the next few days that pass on what overall critics will ultimately think and whether or not this will have an impact on audiences. Although audiences seem pretty sold on the film based on what trailers and TV spots have featured. Right? Right?