Google Currents is above app. The ability to share is great but I am not sure about some design choices in the UI. You have to flip sideways to move from page to page in an article. This probably takes a design cue from traditional magazines but on an iPhone it means a constant flipping from page to page when the natural tendency is to want to scroll down the page with a flick of the finger.
I have also been comparing Currents to Flipboard. Flipboard's interface is simply gorgeous with delicate touches such as the page flapping that very simply suggests that you can flip the page up or down without cluttering valuable screen real estate with UI controls.
If you haven't tried it yet give Flipboard a spin.
Official Google Mobile Blog: Google Currents is hot off the press
http://googlemobile.blogspot.com/2011/12/google-currents-is-hot-off-press.html?m=1(Sent from Flipboard)
....Sent from my iPhone