Hmmm.. i think they're rushing it with their shared universe.
Marvel made 5 movies before they tackled the big one and it worked out pretty well in generating buzz and explaining the characters without needing some form of background scenes in Avengers.
Here it's basically only Man of Steel to become the first chapter with Lobo taking place in the universe too (though i can't see him in Justice League). This means that you'd at least need to introduce Wonder Woman and Aquaman in the movie wasting valuable time setting them up (i guess Superman and Batman really don't need introductions).
With Avengers Joss could skip all of that and dive right into the story picking up threads from the previous movies as he went along.
Here it feels way too rushed and i get a Green Lantern vibe from it.. high hopes and concepts but it turns out to be a mediocre high budged blockbuster which failed.
I hope i'm wrong.. i've been dying to see Batman and Superman together onscreen (and im a 95% Marvel man).