Using Ethereum to play online is a fantastic idea if you hold that currency. The issue of whether or not you should buy the currency in the first place is a different matter. It's an investment opportunity that may or may not pay off for your portfolio. You should weigh up your options and decide what kind of currency you wish to work in before even considering a casino. But if you do go ahead and become part of the network, then it is certainly a fantastic choice to play at an online casino with Ethereum.