for the few niceties that Sparrow iOS(and mac os x for that matter) bring, it's so limited vs the google native app (which is also lacking in certain areas) it's hardly worth it.
Sparrow for Mac OS is perfect. It beats any other email client on Mac platform by a wide margin. The Mac app is what put Sparrow on the map.
Their iOS app - not so much. Apple iOS ecosystem is just too restrictive to allow for a viable non-native e-mail client.