Its not 4% daily but 4% anually ( every year ) but you will get your interest daily. It breaks down to around 0.011% everyday and if you keep on compunding it, it will hit around 4% anually. Not a sweet deal but if you got something to put in then its all good but I wouldnt really recommend to put in big amount just for the sake of getting 4% anually
If it in BTC, when it's enough sweet proposition. At least on bullish market
But as we know, to hold your money on exchange, casino or another such things it's enough risky (this is doesn't matter how trusted the project it is, no offense to freebitcoin. This is life and everything shit happens)