I purchased Letterly while already owning another solution, just to see what it can do. The registration process is nicely laid out and you can manage multiple devices from one dashboard.
The app itself (it's truly an app intended for your phone) looks nice. There's a choice between dark and light mode. Overall the UI is clean and focused around your notes.

Recording
Clicking the Mic button immediately starts the recording. Recordings can be stopped, paused and restarted. All is very easy. It's not always easy to see if you are recording as the audio bars are not always moving, but there is a timer running at the top of the screen as well.

Notes are stacked in one place. After recording you select what you want to happen to the note. The whole process is quite fast and works well.

The end result is good, but as it is a phone app only (at the moment) it has limitations to what you can do with the generated result. You can share it by email or send it to Slack for example.

I didn't see any integrations like Webhooks, Zapier, Make, etc.

A web interface is still in development according to the maker.

In general the app is ok, but for now I'll stick to what I have. The team is very responsive on the Discord and I think the app does hold a bright future is they can keep up the pace and innovate the functionality.