Generally, I liked borg, but I did run into a situation a few years ago where borg would fail to recover parts of my backups because of some unicode error. I didn't knowingly have any unicode filenames in my home directory, but something annoyed it to the point that it would bomb out during recovery. I tried for a few hours using different mechanisms to do the recovery, but couldn't find any way to resolve it.
So, as always with backups, make sure you do regular test recoveries.