Obviously they mean 5 times bigger than unmodded. Map looks similar in size to a full 81 tile map in the current game. Even if it was smaller, its still more than enough space.
I don't see how anyone could be anything but hyped at this point. They've done a great job of incorporating many of the improvements from the modding community, while also iterating and improving on things I didn't even expect them to touch.
The only thing that would keep my from buying it at this point is the performance. I built my computer around when the first game came out, and I would be surprised if it can handle this.