It has a large problem. It tries to save every image as a .jpg, even if it's a .png, and this causes downloads to break if you set it to legible filenames, and if you don't then it will download things as .png.jpg files.

If that bug was fixed, though, it would be perfect. This is the only Twitter Media Downloader that can still save art in one click while appending the name of the artist and the tweet number you got it from to the filename, so it's fantastic for keeping track of where you got your fanart.