I haven't tried any gambling site except bitvest, but it's not easy to win, the chance of winning is getting low as you change the rows and make the wins bigger...But in my opinion, you won't earn big in gambling when you don't invest for your bankroll... and still it all depends upon your "luck"...
Obviously, gambling is not a way to multiply your bitcoins, even if you have a lot of bitcoins but still the chances the losing them is far more then chances of making them more, you may win 1btc/hour in gambling but there are more chances of losing 10btc/10mins, so it is probably not a good choice if you want to earn profit, if you want to play just for fun then go for it without thinking of anything with just a little amount, if you get lucky you will earn also from that small amount and if you are not then you will lose it.