Nice photo and effect! The photo has a great feel to it and the HDR in combo with the film grain is interesting in the warmth that it creates.
The empty space in the lower right bugs me a bit.
If it were mine I'd consider doing one or more of the following:
Make a copy of the ceiling and experiment with adding it back as the floor. Maybe a 180 horizontal flip with lessened opacity.
Crop out the empty space and make it into a 'three piece".
Add something to the free space.
I had some free space in a recent piece that I did and tried to handle it (as shown below)
Nice work though, do you have any others that you want to share links for?
http://www.pbase.com/freddick/image/116416939