I know that there is quick reply in Whatsapp+, but no compose.
It would be great to have that option like it is integrated in EvolveSMS. You can pull down your Notification Bar and there you can tap on a field called "Quick Compose". A Popup opens and you can enter the contact you want to write to and of course the text.
Would love to see this, so we wouldn't have to leave other Apps before answering Whatsapp-Messages