I'm slowly uploading images to my gallery, so I'll be leaving my amateurish feedback in this post. Will edit it once (and if) there is more feedback on my part.
1. All in all, the closer the interface gets to Imageshack's batch uploader or imgboot's uploading interface (without the 5 image limit, of course), the better. That said,
2. Why don't I get the links to embed right away? I have to either a) input manually or b) click on "db" -> get to, say, the
http://www.rpgcodex.net/gallery.php?image=3458 screen -> it is only here that I can get the proper BBcode (under "Full-size:"). And then either repeat the same procedure for the next four images or alter the code manually. Banal, shit, boring. It'd be much better to have access to the full-size BBCode to every image automatically on the same page, right after the images have been uploaded.
3. Where're mah "Next" and "Previous image" buttonz on, say,
http://www.rpgcodex.net/gallery.php?image=3458, eh?
4. The option to drag and drop multiple images or at least to "Browse" -> select multiple images would be cool. + My updates usually contain 100-150 images (or sometimes even more for my FF LP), so uploading them by 5 at a time is a pain in this little ass. But you already said you're working to change that.
5. There's no "album/image created on" info. Personally I don't need it, but generally it's a nice thing to have.
6. Why the compression when uploading? Not that I care much about image quality, but still. My 150 kb jpegs get compress to 40 kb ones. What if I wanted to keep them in higher quality?
7. I'd really, really like the images to keep the original names in the links. E.g., if I upload "uukrul025.jpg", I'd prefer to access and embed it as "http://www.rpgcodex.net/gallery/uukrul025.jpg" or "http://www.rpgcodex.net/gallery/3458_uukrul025.jpg", not simply as "http://www.rpgcodex.net/gallery/3458.jpg". I track screenshots in an update by their numbers, which I can't do if those get omitted in the links.