You do get a lot of free storage to begin with, so it's great for small applications. It's very simple and powerful, but there's a service disruption pretty much every day and there's no point of contact for anything. They just say "use the forum", but 90% of forum answers come from this guy named Hector and he has no idea what he's talking about. I hear the same thing from paid clients, so if you're building something you don't want to be unavailable half the time, just use your own NoSQL implementation.