We use this to send handwritten letters in response to customer queries & requests through a secure channel for compliance reasons (GDPR).
So far it's been easy enough to get up an running quickly without much technical knowledge required - though I wish the onboarding was more streamlined from my end! It takes some time getting used to how things work but once you do it gets easier as your inbox filling out! There is no integration for other platforms that we have come across yet so if there are any tools like that would be excellent. My main benefit of using letter friend here has been GDPR Compliance which means being able to show proof of data protection by sending documents digitally instead of physically writing them down again and again!