Aggressive SEOThe site is 'infecting' Google's search result pages by letting search queries be indexed. This results in enormous web spam. Freelancers can't actually find what they are looking for, but get a tricky redirection to freelancer.com marketpace, where they face jobs not matching their interest.
Money, money, moneyEvery exam taken on freelancer.com costs real money. Cash, that won't come back in any way, even if they push labels in your face showing "You will be 204% more likely to get this job with this exam.". It is so disgusting, that once I felt into their trap. Since I had had my PayPal account linked, I could accidentally click a link in one of their newsletters which instantly pulled money from my account (for an exam fee). They also charge a fee for every successful job done, and some extras for bid highlighting and more, which are almost required to get a job. Unless having your bid on the first place glowing in yellow and owning 20 badges beneath your name (which costs more than $100), you can't even get a single data entry job. That's the mentality!
The scam rate is highDespite freelancer.com undoubtly has the most jobs for online freelancers, lots of the employers want you to work for free. Especially at lower-paid jobs, there is a tendency, that they ask you to start working before getting hired, which is against the Terms of Service - but lots do it. Then the offer get cancelled, and every track disappears.
The XP systemIts built-in experience/level system rather reminds me of an online game than a serious business. Users do a wide scale of actions, publish personal data, pay for ridiculously easy exams, for this kind of reputation.
The conclusion is that you are not able to work on freelancer.com without an investment ($150+). When you've done the deposit, a new door opens for you, and you can start running for your money like crazy!