I used it for a bit. Didn't have a problem with it. Never got anything from them but that was because I didn't get around to earning enough and found it to be to much work particularly because it became about finding specific versions of the product (which hey it is all about market research, so fair enough) and most frustratingly when you do it doesn't recognize it and you would have to file a report, if you cared enough (to be fair this happen probably less than 5% of but it was still annoying).
It is going to need a lot of permissions because it probably uses nearly every aspect of your phone.
At some point I might start playing around with it again.