Amidst long time fan speculation since the first teaser in regards to Batman V Superman, and the whole Michael Shannon debacle. Its finally confirmed, the creature that will fight the God's is evil itself, Doomsday.
Now, when I read comments online and JeremyJahns review of the trailer, I cannot but simply look in shame at how much everyone hates DC, I most of these guys have actually never read The Death of Superman storyline, so they are in no way shape or form to understand why Doomsday looks the way he does in the trailer.
A bit of History...
In the comics Doomsday was conceived in Krypton even before there was a race of Kryptonians. He was initially a test subject to survive the harsh conditions of Krypton (this as we know gives superman his amazing abilities) but each time he dies he is cloned again, adapting to each situation to make him the ultimate being where he did not need any food, water, or even air to survive, killing his creator and escaping. In this course, Doomsday was unleashed in the universe almost destroying the Lantern Corps using their own ring, were not for the sacrifice of the Guardians (which raptured space time).
Later he arrived on the planet Calaton where he destroyed most of the planet save for the capital where the king & queen resided, they combined powers to 'kill' and banish his Doomsday's body in space (which later on landed on Earth and thus the death of superman storyline)
Why does doomsday look terrible?
Well, first of all doomsday has always looked terrible, I mean this isn't dracula we are talking about. Doomsday only develops those 'spikes' because of his evolution and his insane ability to adapt to any environment and any situation. In the trailer we see him with only a little bit of the spikes, but those are because he was just born, I believe Lex extracted Zod's Kryptonian DNA and in an attempt to make it better than superman had to make changes to the physiology to make him the 'ultimate'. So yes maybe by the end of the battle Doomsday could transform into the version most people like Jahns or fanboys who don't read a comic will appreciate.
Why doomsday shouldn't he be a justice league villain, because of his raw power?
I believe he could have been, no doubt. But this is the start of the DCU and its late, Zack Snyder had to pull in the big guns to get the films rolling so that we can have a bigger universe. This would mean starting with a major indestructible villain that will lead to the formation of the Justice League (hence dawn of justice), there is no other villain better than the combination of brawn and muscle of Luthor and Doomsday. And also not to mention the battle is not just superman, but also has Batman and Wonder Woman joining the fight, not as enemies but as a team.