As a software guy, I don't want this post to dishearten you. You've got a good start on something. I like being able to see which assets I have and pick and choose things easily, but I'm sure that the more pain points you relieve the more you will be able to charge for this product.
You said to mention feature requests, (I'll mention bug fixes as a bonus :P ). So here goes...
Bug fixes:
Audio import - In the audio tab, it only lets me pick image extensions. I just checked the video tab and same.
Feature requests:
Bulk update of keywords after import (ie: I have 5 abominations that I want to mark abomination, but I have to manually tag them one at a time)
Bulk update of Copyright Details / Copyright Link. I don't want to have to manually enter them one at a time. In all honesty, I consider this more important than adding keywords in bulk. With the import folder function, I could just enter the Copyright details once and be done with it (Saving me 1,000s of entries x 2 for each file).
Adding the ESC key to the detail page would add an extra 5 seconds to my work flow and I'll be dealing with 1,000s of images - that's why I bought your software.
It would be nice down the road to somehow track which assets I was using in each of my game titles and build a credits text output that I could copy/paste into my game. It would make it so much more worth the effort of copy / pasting the information for the copyright details / link (especially since I have to do that one at a time as well).
If you want some example data, you could use this set of assets ...
