And it shows!
Whilst the dream sequences are - quite intentionally - vague, they are supposed to make you go "WTF is going on here?" – you know, like that completely random, unexplained dream sequence Thor has in AoU, that nobody complains about!?!
Other than that, EVERYTHING is explained... absolutely everything - and it doesn't take much concentration to watch the movie and see it for yourself... but I guess if you go into something with preconceived ideas of what to expect!
Seriously the film has one plot, with two or three small sub-plots twisting through it, that all lead to the same place anyway... you couldn't follow that Lex was setting up Superman right from the outset in the desert? Or follow that Lois was investigating where the bullet was from, or Lex manipulating Wally Keefe etc.? Seriously - you couldn't follow that?
The only curveball could be Wonder Woman, but I thought she was introduced superbly – for example, how many movies did Black Widow appear in before AoU? And only then did she get any decent character progression/explanation –*WW felt more fleshed out in a few short scenes than her, Hawkeye or Falcon for example.