Well, a wallet stored on a website is anything, but not safe. It doesn't matter what service it is, whether its operator is fair and honest or a scammer, it just isn't safe. If I may give you advice, get at least Electrum – it's fast, yet you always hold all private keys to your coins.

Edit: aubert's screenshot refers to this event. It's good to read more information about what happened so as one doesn't trust on-line wallet services never again.