MobileRSS is on sale for $0.99 today. I have no idea how long the sale will last, but I’ve been using the free client for about a month now and it’s the only Google Reader (greader) RSS client for the iPhone that I’ve found useful/worth using.
The biggest feature that won me over is the fact that it syncs so seamlessly and quickly with the web interface. I’ve tried 3 or 4 other greader apps and they’ve all been slower and less reliable than the mobile Safari greader interface.
MobileRSS just works, and it offers Instapaper, Facebook, ReadItLater, Email and Twitter integration. Try out the free, ad-supported version first.