I got mine this morning and just set it up. For context, this is Block's 2/3 multiseg self-custody wallet - one key at the phone, one at the device, and the third is their servers. Link: https://bitkey.world/
My pain point is essentially having a real easy way for someone in my family to go to an app, and get my stack if something were to happen to me while keeping things in self-custody. Basically, a cash app experience but I keep the custody. Them touching a usb-like is really not ideal, and it scares them and me.
Thoughts after setting it up,
Does it solve my problem? No, not really. You can use the app to spend bitcoin up to $200 daily limit without the device. (1/3 keys). So, that would work. But that means you are also trusting the server to send that much. Is it the right balance for a lot of folks? I think so. But, the UX problem is still there, someone will need to know what they are doing to use the Bitcoin if I am not around. On a daily basis, they have to send a $200 to an exchange and go through all that jazz until the stack is gone.
My feature request for Block's folks is to allow people to set the daily limit a little higher (especially with how high Bitcoin prices are going). I think $500 is reasonable - and allow you to sell in the app - similar to cash app. You can buy now, but can't sell which is a little weird and my guess is regulatory stuff.
The other issue, you sign transactions via NFC - which takes like 3-4 tries to work. Unlike something like Apple Pay - you bring your device to your phone and hope for the best, no clicking or any kind of feedback. After a minute, it times out and you go through the whole process again until it works. This is kinda of expected for 1st generation though (and maybe just my device), and I expect to get much better soon. It is really not that much different than the square devices that are around and work great.
Wish list stuff is lightning support, as well as P2P buying and selling - and then we would have a great experience.
Trezor + Phoenix (the competition as far as I am concerned) has a bunch of smaller cool features that would be nice to get on Bitkey app as well.
Other than that, it is super cool device and app. If your problem is not being able to spend your bitcoin because your self-custody wallet is not around - it definitely solves that. But - then again, you should be really using lightning to spend those sats, and the current self-custodial lightning apps are pretty decent.
My personal plan is to wait until lightning support, and then see if I can replace my Trezor + phoenix setup with just bitkey to simplify things. I think Block would get there eventually. Nonetheless, I am still waiting for someone to build something that is self-custodial that is dead simple UX that I can give to my 60 year old dad.