The new Facebook Messages incorporates email, SMS and Facebook Chat and Messages into one convenient bucket. It's a smart idea, but you should think twice before you consider ditching your current email address for Facebook email. Here's why.
Note: Facebook Messages' email integration is rolling out on an invite-only basis; you can sign up here.
Facebook Messages Is Not Email, and Can't Be
The new Facebook Messages may integrate with email, but that doesn't mean it is email. Zuckerberg and company won't argue this point: Although the new Facebook Messages can send emails from your @facebook.com address to any email address, and receive email from any email address sent to your @facebook.com address, it's still not email. In fact, it doesn't want to be. The new Facebook Messages isn't about killing Gmail. It's about extending the reach of Facebook Messages.
Every email someone sends to [email protected] will go into Facebook Messages as part of a single conversation. If you were to send me several emails at [email protected] from your email address, I'll see all of those separate emails as one conversation: a conversation between you and me. Separate emails with different subjects are meaningless in Facebook Messages (though subjects sent from email clients outside Facebook are bolded in the conversation).
Point is, you can't use Facebook Messages like email because, while it interfaces with email, it's not email. This isn't necessarily a shortcoming of Facebook Messages; it's exactly how Facebook intends for it to work. But if you use your email for more in-depth conversations (as opposed to quick back-and-forth, chat-style conversations), or you like to communicate with the same person using different threads, it just won't work.
Facebook believes that most conversations with friends are on-the-fly, short, real-time conversations, which is why they're not terribly concerned with making Facebook Messages work like email. All they're doing is making sure it works with email.
You're Putting All Your Communication Eggs in One Historically Walled Basket
If Google had announced a product that similarly integrated SMS, email and chat in a more convenient one-stop communication shop, a lot of geeks who are completely against the new Facebook Messages would be extremely excited. (It's worth nothing that you can currently send email and SMS, chat via GChat or AIM, and make phone calls all from within Gmail's existing interface; the fuller convergence just isn't there.) Photo by Mrs. Logic.
It all boils down to trust. A common problem arises with services that intend to converge separate buckets — in this case, all of your text-based communication. The convenience of one point-of-origin for sending and receiving messages across communication protocols is unquestionably nice, but the tradeoff is that you're putting a lot of eggs in one basket. In this case, the basket is Facebook, and the eggs include email, SMS and Facebook Chat and Messages. And historically, Facebook hasn't been all that open about letting you get information out of the service.
In a digital world, communication boils down to data, and as such, data portability is an important concept. Facebook has recently opened up a little more, allowing you to download some of your information from the site, but the fact is — if you decide to leave Facebook — the service has never been good at letting you take your ball and play elsewhere.
Facebook has said that they plan to introduce IMAP support for Facebook Messages, which means that you'll likely be able to both send and receive as well as back up your Facebook Messages using a third-party application or service. Sounds promising, but we'll believe it when we see it.
Your Workplace Will Block It
According to a report from last year by DNS service OpenDNS, Facebook was the second most commonly blocked website on the internet, second to MySpace. You won't find an email provider among that top 10 list.
That doesn't mean that every workplace blocks Facebook or that no workplaces block Gmail, but the prerequisite to communication is access, and a lot of people who can't access Facebook from work can still access their email accounts. In theory, Facebook Messages could get around this problem by sending you messages via SMS, but unless you want to do all your "emailing" from your phone, that's not much of a solution.
Facebook Messages is a smart move, filled with good ideas and an interesting model for evolving how we communicate with friends. If you rely on email to do anything more complicated than what you can already do over IM, it's also the last thing you should use to communicate.