I got one recently and filled it out. Got the FPPs as promised. So the Zoomerang surveys are legitimate. I would never input critical information, but they've already got your username and email address.
However, I don't like the phrase "You can only receive the link by logging in to the Poker...".
My email included a direct link to
http://www.zoomerang.com/survey.zgi?p=....
for my survey. Be very careful if they're asking you to LOGIN to another site first. That sounds like phishing. If in doubt, email stars.