People who keep suggesting other clients don't really get the point. The native client offers a better experience for a lot of reasons:
Actually Supports 6/6+ displays
Functions well with swipe back gesture
Quick gestures for mark as read, archive, delete
Great functionality with Notification Center.
There is no great way to get Push Gmail to your phone for free.
Some people forward it to their icloud email, but then you run into other small quirks as well. I just do fetch every hour, most of the time it's junk email anyways.
Accompli has all those things and more. Tried it instead of the gmail app a week or so ago and don't want to go back at all!