AnonyMint seems abosolutely convinced that PoS cannot work.
If he says so, it has to be true. PoS should shut down all operations within 24 hours and go home.
My understanding is that PoS has attack vectors that are not present in PoW, giving the attacker a cheaper way to totally control/destroy the network. On the other hand, even credit cards "work", in a way. Nothing is perfect, even PoW.
One way to attack a POS coin is to hedge a 51% attack using derivatives. In this scenario the attacker purchases the coin and hedges the position by selling short in the derivatives market. The net effect is that attacker's stake does not equal the attacker's exposure. The main reason this kind of attack has not happened is that none of the POS coins have developed to the point where a strong and liquid derivatives markets has developed.