It's GM Mode on steroids and without the competition with the other show. You control all shows and you do as much with them as you want. If you want to focus on one specific story involving two wrestlers, you can. If you want to do several different stories about everyone in WWE, you can do that too. I haven't messed with it yet, but from what I understand, it's really in-depth.
Yeah Create A Story mode is brilliant. I've been at it all weekend, creating a Cena vs. McMahon storyline, leading up to Wrestlemania. Still got a bit to do, but it really helps if you've got a USB keyboard. Otherwise scenes will take forever to write out. Another problem is that there are only about 30 scene templates to choose from, and the animations get a little repetitive after a while. However you can change camera angles, facial emotions, Sound effects, etc.