Fairly poor. Same can be said for most of these freelance type auction sites.
It is a festival of people trying to screw each other.
One nice thing about them is, unlike US based services, they don't ask for a lot of personal data, so if/when their site is compromised, or one of their freelancers decides to get greedy they can't sell your SSN to people, your identity is pretty safe with freelancer.com (provided you don't give them bank info or something)
I just had a client apparently walk away without paying, I've heard the same thing happens to buyers.
One thing I know about is that buyers get "suckered" by the low prices, the code often has (obvious) security flaws.
I know this because I've cleaned up a few of the messes left behind. (can't say as I feel TOO bad about it.. if you have a $1500 project and someone bids $60.00, well, you get what you pay for)
Security flaws *can* be particularly problematic, in some cases a business owner looses everything and has to start from scratch. It's really important to work with programmers on an on-going relationship basis, building up trust and yes, friendship.
This is one of the reasons I don't trust the auction places, for all I know, they hire the freelancers themselves, on a "lowest bid wins" basis, which means that any info you give them isn't very safe.
The way they work it, on commission really stinks. It would be FAR better if they just charged freelancers a flat rate, say $0.25 for contact info, no bidding, no message boards, none of that.
Then you could form a more personal, unimpeded dialog with the buyer and decide if you want to work for them. (and buyers wouldn't be flooded with boiler-plate bids, because freelancers would have to think twice before buying the contact info)
The current setup really encourages people to screw each other.
