The characters don't stand out enough from the background and it looks like it's above water - that being said your HUD is beautiful, perhaps for the HUD and characters a black or near-black outline would bring them forward, at least for the HUD. Break up the floor tiles with some cracked times, holes in the floorboards, dirt, grime etc if you go to edit this anymore. Great work for your first mockup!
since Rapture is destryed and stuff, you'r picture could use some corals, broken floor, strip wallpaper and stuff..
and the windows looks just too perfect. 4*
I love it! I would love to see some of the art-deco style a bit more though. Excellent.
I love the simple yet detailed feel of this piece.