I didn't even know there was a mobile phone app thing to be honest - but generally speaking, I like being in a survey.
Whenever I see a survey result I disagree with, I always think "grumble grumble, they didn't ask me, did they?", so it's only fair that I at least attempt to be in some of them :)
I started with enthusiasm but it was pretty relentless and I only do the occasional one now. If they'd let me know which were Important then I'd jump back in.