Monzo UK user who has moved to the US for the year of 2020. Received my Monzo US beta card recently and have only been using it for a couple of days now, but here are some of my initial thoughts. I’ve tried to avoid repeating things that have been mention before in other threads.
iOS widget
Pleasantly surprised that depending on which account I was last looking at, that’s the “Account Balance” & “Spent Today” that is displayed on the widget.
Would be nice if the widget was expanded so that it could drop down and show the balance of the other accounts. Just with the most recent taking top of stack preference.
Sending money
Sending money from my Monzo UK account to my Monzo US was pretty easy, fast (took less than 24 hours), and had a great rate thanks to the integration with TransferWise. Would only suggest making the set up of the transfer a little simpler and more intuitive. I had to write out the routing and account number.
Since they’re both my account and both in the app it would be nice if the app could pick up the routing and account number, and have an option to “send to yourself”. I don’t have a joint account with my Monzo UK so I can’t speak from experience on how money is moved between personal and joint accounts, but I’d have a strong feeling that it’s also that simple and intuitive.
UI
On my physical Monzo US card the “monzo” is left-aligned, be nice if the in-app card UI and Apple Pay card matched that.
Anyone else in the same boat of having both a Monzo UK and US account feel free to add any of your thoughts 
