Both game compatibility and sound emulation have improved, and are a lot better, with some games (ex. Mother 3) no longer crashing.
There are still a few bugs left to fix, such as sprite flickering in certain games.
Google around and see if someone's made a save editor.
If no one's made a save editor, then you'll have to reverse-engineer the save format on your own. This could potentially be very easy, or it could be borderline impossible.
Just a few weeks later, the DMCA takedown hasn't changed anything.
Use the latest official Citra if you want a polished experience.
Use PabloMK7's fork if you want more mod support.
etc. etc. etc.