I don't feel it's missing much feature-wise. It could use some polish in the HMI department, though. Not for me personally, but I can imaging the Windows NT theme could be a bit off-putting for the average user.
I would agree with this. Almost always there is a way to do what I want but it's not necessarily intuitive.
Tbh, it's just fantastic.
I'd welcome a more formalized way to backup /export /restore my entire database so that my library can be moved between drives and instances. I do it manually like everyone but am always a little nervous/uncertain when I do.
I'd like to see Calibre use the Save to Device Template when transferring books via the web content server. I really like my books to come in named according to the template but I prefer using the content server to download books as I keep my server in a physically difficult to access area.
Ok, seems like I'm starting this off (or maybe not - given the fediverse state) - here goes with my perfect calibre...
So far, I sync it via pc and android. Works well, but I have to use proprietary software (read era) to read my books. It syncs (via gdrive which I don't like) and therefore don't use.
My 'want' then...
Calibre with an in-built reader with sync to either webdav or Nextcloud (so I can keep my page position across multiple devices).
The reader doesn't have to be state of the art, just usable - like read era is.