I still think their "Bitcoin computer" was ridiculous and still resent their shill campaign on Reddit for that overpriced $400 Raspberry Pi of theirs.

They're not all bad. I do like this page they've made: https://bitcoinfees.21.co/

The concept isn't a terrible idea. It's an interesting service especially if it were used by otherwise hard-to-reach people. I can't see a lot of people, (messagers or messagees) using it, but it's worth a try.

But it looks like they're promoting this to the #1 purpose of 21.co and perhaps their company, which is hard to imagine the money dumped into it is justified.