I used to run a much older version of this on Firefox 50-something. I preferred the interface since it would open up a separate window I could move to one side and keep an eye on downloads as they progressed. Now I have to keep on switching tabs. Maybe that's just a web extension thing, but I miss it.
My main complaint, like others, is there is no way to designate where to send downloads other than a sub folder in my Downloads folder. I use other extensions that download files provide a save to window so I am not clear why this one does not anymore. I still use the extension regularly, but not as readily as I used to unless I really have a lot of files to download at once.
There also used to be a feature where if I had a save file widow in Mac Finder that it had a selection to use DownThemAll to handle the downloading. That again meant I could monitor the download in a side window if it was something slow to download.