Is it just me or does this still look very Web 1.0-ish to you? Facebook could've done so much more, maybe categorize its listings a little better? Maybe give the über marketplacers or some "elite" Facebookers the ability to create new categories? Because that's the one thing that annoys me about Craigslist - I have to spend hours sifting through crap that is irrelevant to me to find that one listing that really really is what I'm looking for. Maybe Facebook could've added some mashup like functionality to it (for its apartment listings)? Maybe some snap previewing so I don't have to click on the page or open a new tab? Better searching? RSS? (even Craigslist has RSS) Don't get me wrong - this is still a HUGE step in the right direction for Facebook users, the majority of who are college and/or highschool students.
Rock on, Facebook. You're making it all about the user.
Update : And, while I'm asking for stuff, how about facebook marketplace for mobile? I just checked, and it doesn't seem to be available (yet).