They pretty much ignore the simple tenant of web design:

make it dead simple for new users

and powerful enough for the power-users*

It's sad, but it's the best place for apartments in nyc.. and the listings are incredibly polluted: apartments listed in the wrong neighborhoods, without a location, lies about nearness to subways ("steps from the subway!" - but when you look up the intersection they list [if they list it], it's a 10 minute bus-ride away from the nearest train).. flagging doesn't seem to help any, either - they just repost the same ad, over and over again...

*In Craigslist terms, this of course is the peruser, not the poster.