I have been using Reeder as my primary RSS client since the first beta version became public. There is a lot to like and a lot of odd things about the app. It feels just like the iPad version — and that is not a bad thing.
I will say that the app itself feels better in Lion than it does in Snow Leopard — where in the latter it seems slightly out of place from a design standpoint and in the former it fits right in. MacStories has a nice write-up about the app if you want more information.
The price: $9.99 — seems like a steal to me given all this app can do.