This is offered for free...
Is there a catch?

Seeing as it's Google there might be SpyWare on it, as there is with Gmail. But I can't say this enough, if there is spyware on it, as there is on Gmail, it isn't malicious at all, and it doesn't infringe your privacy. It's simply used so that they can send you advertisements via your email so that you don't have to pay for the service.

There's spyware on Gmail?

I think there is but its not malicious at all.

No-catch but I'd look around becuase everything offered there has a free equivilent that may be better suited to your needs.