Android phones, apps and tablets

That expansys deal on Galaxy nexus looks awesome.

For £30 more you can get the multimedia dock, a smooth case and a spare battery thrown in. Nice.

Can anyone explain why a spare battery is useful, if I can't charge it outside the phone? Just keep it safe until the original battery degrades?

Reviews all suggest Nexus is only good if you like vanilla Android though. techradar basically say you're better off buying the S3. I'm over the deal.. for now.