Well... this looks a little strange because I'm very used to the usual green scheme of deviantART... It's nice that this Stash comment interface has a light color scheme, but maybe it need a little bit more of contrast between the text on the comments and the bubble behind it. Maybe making the text darker could work a little better and making this much more comfortable for the reading.
Now, about the rest of the interface, I think that has a good number of tools to create a more customizable experience, but I don't know how good can be having different styles of commentaries around the page. I'm using the center align tool and I'm already feeling that it will look weird here... Just saying XD
Another thing that looks very interesting is that you are allowing to explore your gallery, your favorites and the emoticons with the interface on the right. As far as I can see, you are trying to give an access to all your stuff from this panel. This could be useful but it would be better as an optional display, I don't know, like a drawing program where you click on an icon, on your right in this case, and it opens that panel with all that we have on the right. Just to don't feel like you are closed in a limited space.
However, thank you guys for keep trying new stuff on the site and for letting us know how the new things that you're trying to add would look. Keep up the good work