They added a prologue before the Raft quest line and they added some cutscenes to it.
Well most people go theirs due to movies / comic releases and they wanted to coincide with that. Though not fully sure why was picked last? Might've been dartboard failure and not having enough Deadpool on it for the dart to hit :P
Though I guess we could blame Fox too for not putting out a Deadpool movie a lot sooner so they could release a 52 to coincide with that, haha.