KiraNoot said:
Feedback is welcome.

I'm not a huge fan.

First things first; holy shit, is this form daunting, over two pages tall filled with six different textareas. First thing you see when you open this form is a big red warning box before you've even done anything, and below that seventeen buttons clumped together. That red warning section should not be there from the start, it should only pop up if a user tries to upload without first adding a source. As it is it's very distracting making it feel like you've done something wrong before even choosing the image you want to upload.

Second I'd probably get rid or at least collapse of some of those textareas I assume the first five all do the same exact thing other than maybe putting the aritst: or species: prefix.

The Sex, Count, and Pairings section should probably have the count buttons first and, in fact, before selecting solo, duo, or group the buttons for sex shouldn't be visible. Same thing goes with parings except either duo or group would need to be selected for these options to appear. Similarly the intersex/male, intersex/female, and intersex/intersex should also expand other options since these tags probably shouldn't be used on their own.
This will cut down on visual clutter, making only the options that the uploader might need available. It might also be wise to put alt-text on the buttons to give a brief description of what they mean when you hover over them.

The Ratings section buttons should probably be radio buttons, it'll make it clear that these options aren't the same as the other ones and since the function of radio buttons is so ingrained in pretty much ever computer user's mind that it's understood that one of these options needs to be pressed. Also probably have alt-text on these things too.

As it is the Fetishes and Themes section seems superfluous as it is. I'd say put some buttons there but have them collapsed into a few different categories.