I simply love this new feature in google reader. The new feature provides "trends" which is very useful in visually analysing our reading trends and subscription trends.
Reading trends gives you data like how many posts you have read/starred/shared in the last 30 days. I currently have 18 subscriptions in my Google reader and I have read 840 posts in the last 30 days (I feel good about it).
Subscription trends gives you data about the feeds (how often they are updated). This is a nice way to identify whether you have some dead feeds that have not been updated which you are better off removing from your list.
It also provides interesting graphs about what time of the day do we ready our blogs and what day of the week we read them as well.. (pretty interesting to see my midnight bar soaring above the rest).
You can read more about it here.