There's nothing wrong with this movie landing in the low 70's on Rotten Tomatoes. The expectations are getting a bit too high. Regardless the positive feedback we're getting from tweets and even fellow hype members... There is still a good chance there will be people out there that aren't thrilled with this movie.
The Amazing Spider-Man landed in the low 70's and that movie still made 750M WW with a sequel already 3 months into shooting. That's all that counts for MOS, it makes enough money so WB gives it a sequel... That's where the real money is. Put a crazy villain for the second one that challenges Supes on an intellectual/psychological level instead of going fist to fist like he will with Zod.