IMO with environments which are supposed to be worn and old, the thing that usually bothers me is that everything is equally worn or dirty and this makes it look a bit fake.
For example the top windows all seem to have the exact same amount of dirt, in reality some would be less dirty than others.
The ceiling wood also seems not high rez enough, and also too evenly worn.
The old wood floor, I'd add a little bit of coating to make it look like old varnish which gives a thin film interference effect. To add a coating in this case, here is a blog post by Tom that explains the details (very useful info!):
http://blog.maxwellrender.com/tips/push ... materials/