A couple of other neat features that have made me glad I switched:
Shared items
You can mark individual items in your subscribed feeds as 'shared', and they become available on a public page. Like-minded people can then subscribe to your shared items feed, instead of you having to keep forwarding them links. I've added a link to my shared items over there on the left.
Starred items
Like many of you (I'm pretending here that people actually read this: humour me!), I keep a bookmark folder where I drop things that look interesting but that I don't have time to read straight away. The problem is that it doesn't help much when I see something at work that I want to read properly at home (or vice versa). Since most of them come from RSS feeds, all I need to do is click the star next to the item in Google reader, and it goes into a list that I can come back to later, rather than trying to remember which feed it was from. I guess many standalone RSS readers have a similar feature, but it comes into its own when you can access the list from anywhere.
Technorati Tags: Google reader, RSS