How well does it integrate with other financial services? I currently just use Mint because it's the only app that can consistently pull in all my accounts into one place.

It has the ability to import data, but it's not perfect. The author actually discourages using it: https://docs.firefly-iii.org/importing-data/csv#best-practic...

would love a replacement for Mint but never find anything that doesn't require a lot of extra work