After a lot of ballyhoo late last year, it looks like Facebook is set to roll out its new Messages feature on a large scale – most of the social network’s 500-plus million users should receive it in the next two months, with early recipients being able to (at least in theory) sway the distribution somewhat via suggesting invites for their Facebook friends. Trumpeted over the last few months as Facebook’s “Gmail killer,” the new Messages takes a cue from the email giant and threads messages by conversation, as well as separating out convos you have with your friends from messages you’re sent by events (including events created by pages, not people) and groups. And, as promised, “real” email is part of the package; when you make the switch, you’re offered an email address at your custom Facebook URL, if you have one (if you don’t, now’s a good time to hit facebook.com/username and pick from what’s left).

So is the new Facebook Messages the game-changer we’ve been promised? It’ll likely be tough to say for a while, if for no other reason than that the Messages interface – which until now hadn’t changed much over its life span – is fundamentally different from what we’re all used to. What’s more, if you’ve been even remotely tidy with your “old” Facebook inbox, it’ll be a shock to be hit upon upgrade with pages and pages of messages you’ve sent and received (and thought you’d deleted) since … in my case, sometime in the middle of 2007. (It’d be interesting to hear how far back others’ archived messages date.) Additionally, the “two mailboxes” model is a little rigid for anyone who’s used to receiving messages in a single inbox. It’s easy to ignore the second mailbox, which includes messages sent to your @facebook.com address via traditional email (unless they’re from addresses associated with someone’s FB account), as spam. And while it’s extremely convenient to now be able to send the same message to a mixed group of friends who are both on and off Facebook, the ones receiving via email will only see a generic subject line: “Conversation with (Your Name).” (The same doesn’t apply the other way around, though; send an email to an @facebook.com account and that Facebook user sees your subject line in bold at the top of the message.)

Have you made the switch to the new Facebook Messages yet? We’d love to hear your thoughts, praise or frustrations – as with everything else new that Facebook has turned loose of late, we’re all getting used to it together. Drop a comment via the link below.