Has anyone tried casino skill challenges?

Have you heard of social casinos? A friend of mine has been telling me about American Luck for the past week and has sent me a link to register. He said he would receive bonuses for doing so. Having only played at classic casinos before, I decided to give it a try. I didn't expect the slots to be so similar to those in classic casinos, but it's great that they're free. I found games like Hot 777 Casino. So far, I've played two classic slots: Sizzling Sevens and Hot Triple Sevens. They're both very convenient to play and track your winnings with. Does anyone on the forum have experience with these slots? I've already spent all my registration bonus coins on them. However, I'm thinking of trying something else with a Viking theme. I think that would be interesting, too.