But they have really high payout threshold 0.03BTC which you can't reach without either inviting others or mining with your CPU (they are mining monero with it).
Well, if you exclude both those ways of course you are excluding 80% of site mechanic, it doesn't make much sense.
Mining as it is configured now with 1 spin every 2200 hases, it's way more profitable than referers, because in 30 minutes of mining on a medium-end cpu (i5) I accumulated 206 spins, whilst with the 3 free spins every 3 hours it would have taken more than 8 days to accumulate that amount of 206 spins.
And for the 0.03 minimum threshold, it's not that unreachable IF (VERY BIG IF) the system is not programmed to decrease the odds the more you approach the 0.03 threshold, but we will never know this because there is nothing to sustain the provably fairness. But you should also consider along the high minimum threashold, that the minimum payout for a winning roll is high too, that is 3499 satoshis, not the ~30 satoshi as in other faucet sites. A certain fact is that in the first 50 roll you get when you first register, you're strangely VERY lucky and could possibily win in the order of ~300k satoshis.
I started a couple of days ago and with no fixed referral bonuses (got 3 invited) and mining only from this morning, my balance is now ~0.0108 BTC, that is about 33% of the goal. Ok maybe the fact that this is too good to be true, it should make me suspicious?
A thing that makes think bad is that they didn't open an official thread in here, nor have a facebook page or twitter account. Ok they are generally also meant to sustain a well designed scam and maybe this is not to be taken too much into account.