The profile import from -1.x (almost 8G) was flawless, afaict, and the new suite is quite nice, with a few niggles like File for email not including the full folder tree when in the message. There is one more weirdness, atm, that exposes how much force of habit, muscle memory enters into usability, for me.
The suite component icons at the left of the status (iianm) bar are like this in Navigator, Mail, and, just checking for the purpose of this post, the less-frequently-used Composer, Address Book, and Chatzilla windows. When in an email Message window, it's like this:
Not quite the end of the world but I often use these icons to switch windows from the message window, so I notice it.
