I played with this for all of one day, I would say I'm a pretty heavy user on this blog ish so that was a lot of usage. The gist: I stuck with Bloglines


I'm a bit late to the party, Google Reader has been around since 2005 (writeup) but it's only been good since last year

Tie
- keyboard shortcuts, Google Reader keyboard shortcuts: j (prev), k (next), v (view original post), u (full screen), r (refresh), 1 (expanded view), 2 (list view), s (star), shift-s (share), g* (go)
- sharing favorite items: Bloglines use Clippings, Google Reader has starred (private) and shared (public) items.. Bloglines should have a slight edge here cuz the saved items are organized (folders)
- adding feeds
- unread feed number is updated in the title tag, both could use that information to the front, as in "(4) Google Reader", Bloglines is shorter but the whole string is "Bloglines | My Feeds (..."

Google Reader > Bloglines
- playtagger works (it doesn't in Bloglines)
- in fact javascript enclosures like Youtube work, js is stripped in Bloglines
- Google Reader works offline with Gears, things stay sync'd (more)
- trends, usefulness is debatable

Bloglines > Google Reader
- saved items is not a persistent state so you keep having to uncheck the "mark read" checkbox in Google Reader, can always star the items but that's hacky
- dedicated iPhone site for Bloglines, the Google Reader mobile version is useable but ui could use some spiff; also there is no way to read by categories on Google's mobile site, it's all that "river of news" crap; ish really needs to be formatted for the iPhone google.com/reader/m
- reading, the scroll effect is so hot on Bloglines

Based solely on the iPhone experience, I gotta stay with Bloglines

More Google Reader
- LifeHacker
- Wikipedia


Update
8/26 Bloglines Beta (βloglines if you will, how cute) at beta.bloglines.com. Hmm mimicking Google Reader hard. Announcement, forum