In WWE2K15 has except the smaller roster, 2 new game modes (exclusive Who got NXT & 2K Showcase) not really done much.
The WWE World has a new feature to you can now make his actions by rivalries, alliances, etc.
We were promised improved graphics, but is only minimally to see some of it.
There was much of the predecessors rausgenommen like Create a Finisher, several Entrance, the juke box can no longer be fed with own songs (One hears only the in-game soundtrack), an original story can not build one.
Is nothing has changed in the match types, you still have the same choice as in WWE2K14.
The many bugs I will not mention further.
It could have been there longer!