Looking through the pics (which, remember, were chosen to try to *sell* the house) it looks to me like it's a complete gut-and-rebuild job. New floors, new walls, probably a lot of new electrical and plumbing. Obviously paint, carpet, smoke and CO alarms to get up to code, maybe other code requirement work, exterior siding and maybe roof work, windows, etc, etc.
The pictures show a wreck. It would be interesting to see what else is going on that's not pictured!
I'm not experienced with this big of a project but it my WAG here is that you'd be looking at $200,000 to fix the place up decently (and to current code), unless you want to spend the rest of your life DIYing it. It *still* could be worth it to someone, but people have repeatedly backed out, it appears.
Probably too good to be true.
-W