Google Reader 5

Although not perfect, Google Reader gets 5 stars for totally changing my approach to RSS feeds. Prior to using it, I relied upon Shrook, but based upon how I use computers (meaning i have a bunch that I access from different places), having an application installed deskside really prevented me from accessing feeds at any time I had a spare moment.

I transitioned over to Google Reader pretty much immediately after their launch (I'll pretty much try anything google launches at least once :)). Following this, having access to my RSS feeds in the cloud has become even more beneficial because I was an early iPhone adopter.

Best features:
direct links to email each post
bundled subscriptions (check out the "cool items" subscription for a great overview of trends in blogs on any given day)
sharing (everyone who has used Google Reader from the beginning knows that this was a rather rocky start that involved sharing with EVERYONE you've ever emailed from a gmail account, but they have since worked out the kinks)
Statistics on what you read, and seemingly a smart homepage that detects and delivers your favorites up front.

A few gripes:
The automatic mobile formatting of blog posts that you click through to on an iPhone is practically unusable. It seems like this feature may be great on a blackberry, but I haven't found a way to opt-out beyond clicking a link on an article by article basis. Additionally when i email links from gReader on my phone, they presume I'm sending to another mobile (which I almost never am).
There's not an easy way to deal with certain blogs in a way that suits my preference for ambient information. I'd love a way to set certain feeds to auto-clear after a given amount of time because I will generally just do that manually anyway.

To sum it up. Google Reader is the best RSS reader I've ever used, and I'm completely hooked. They're constantly updating it to try and make it better, so as long as you don't mind learning new things every once in a while about a tool you're comfortable with, you'll love it too.