For serious Reddit browsing, I wouldn't use this, but for a never ending gallery of images, it's pretty great.
A couple of things I would change:
-when you click into an image to go fullscreen, it's not obvious how to go back to the main page. So far I've been clicking on the subreddit identifier which will take you to the subreddit the image you just fullscreened is found in and then you can go back to the overview. Unless I'm missing it, this is awkward.
-A slideshow option would be fantastic, as would an option to show just the images without all the other chrome. Maybe overlay the up and down vote buttons and the upvote count.
-Finally, make the NSFW toggle persist between launches, please.
I should also point out: I've used this on an iPad and now I'm using it on a Mac and, aside from the above, it works brilliantly. If I could get the above, It's a five star app.