A lovely login screen. Followed by a not very well explained request for my mobile phone number, so they can send me a text that has a link to Facebook that makes me login again.

All to log in to my Facebook account, which I am already logged in to in the Facebook app on the same phone.

Do you have login approvals turned on? https://www.facebook.com/settings?tab=security&section=a...

Nope.

I think this explains it - http://twitter.com/#!/bwalkin/status/101012800406683648

Aside from the fact that it's entirely redundant and ignorant of an Android feature meant specifically to appease people who hate repetitiously entering their account credentials. The Facebook Proper app even uses AccountManager properly. Messenger should prompt for permission to access the device's Facebook account and I shouldn't have to retype my credentials. It's the entire point of that API.

I'm sorry, but I'm not typing in my 25 character secure password for another device that will confuse Facebook's Messaging client. I've missed two messages in the last week because it notified me somewhere and then didn't notify me on my desktop when I returned. I just happened to notice because I click on Messages to compose a new one.