For some reason, I've never enjoyed the interface of Google Reader. I love that GR is an easy way to subscribe to all the (what seems like) millions of blogs that I subscribe to, but it's always felt like a clumsy reader to me. It's awkward to sort blogs and you can't comment within the website, which is slightly annoying.
Anyway, so I'm constantly on the lookout for Mac/iPhone apps that I read my GR through. A lot of them are just as clunky, if not more clunky, than GR itself, but I think I might've stumbled across one that I actually like! Have you tried NetNewsWire? One very cool thing about it is that you can create "smart folders", such that you might find in iTunes. I've got several set up based on key words - "graphic design", "movies", "giveaways", etc. I've also got one set up based on blog creator to designate "people I know", which I realize could be done with the regular folder method, but I just love using smart folders.
(If you don't know what a smart folder is, basically you tell it certain rules like "title/description contains graphic design" and then it collects anything that meets that criteria. You can create smart folders with multiple criteria to really get specific about what you want to collect in that folder.)
Also a cool feature of NetNewsWire is that you can actually comment w/in the application! I don't know why but most reader apps make you jump out to a browser to comment which is fine, I guess, but it's definitely easier to stay in one application to do everything re: interacting w/ a post. I like being able to just stay in one application and comment on stuff.
NetNewsWire also lets you "flag" items, which gets ported over to GR as "starred" items, in case you are trying to track your favorite posts like I'm doing. I haven't noticed that feature in a lot of the readers I've tested.
So basically... it's a lot like Google Reader, just a little easier to move around in. You should check it out! Oh, and I haven't tried it, but I believe they have an iPhone version as well. I've gotten out of the habit of checking my blogs on my phone, but I probably should try that so I can let you guys know how it works. ;)
Do you use a reader app or just stick with Google Reader? Is so, which app do you use?