Blockchain.info is as safe as an online wallet -- which means its susceptible to possible attacks either from the server side or from your own account getting hacked.

Blockchain does offer some nice features such as multi-recipient transactions, and adding notes to the blockchain tx, but I'd only suggest using it as a temporary wallet, not to hold all your coins.

You can, however, export directly into Multibit from a Blockchain backup and then create a cold storage wallet.

One thing to be aware of is that Blockchain regularly sends a copy of your wallet to your email address registered with the site, if you make any changes to your account. Make sure that once you've downloaded these, you delete the email, and any old copies! And one definite thing to avoid: do not link your Blockchain account to Gmail -- which can be compromised and then have your wallet/password captured.