Can I update iPhone 4 to iOS 6.1?

I have an iPhone 4 and have waited to upgrade it to the new system. I had just heard about how it takes up a lot of room and how it had battery issues. I don't get great battery life anyways so it probably isn't that big of a deal. Should I upgrade?

Added (1). I'm on 5.1.1

Yes you can and should. What are you running at the moment?

Yep, just did it with my iphone 4 a couple days ago, but if you don't want to, you don't have to because the only thing it physically changes in appearance is when you double click to play music on the lock screen, other than that, nothing really changes, and nothing happened with my battery life.