The only thing this add-on needs is a feature like the one in Powerful Pixiv Downloader that adds a download button on the thumbnail of every picture for faster downloading.
I hope the addon's author reads this.

No matter what settings you use, this extensions ALWAYS saves as a zip file. Extremely irritating.

I like it, but two problems:
Even when downloading "Manga", I don't want a folder to be created, I don't see an option to disable that.
Also for the same, if I download a Manga that is identified as having 4 pages, it only downloads the front page.

If these things are fixed, this is perfect! Especially the ability to download animations, the extension I used on Chrome before migrating to Firefox didn't have that, nice!