I like how easily it integrates with Gmail to save me from having my emails sync across many different devices over other apps that don't support syncing so well (WhatsApp).
It's also great at keeping track of sent/read messages in your inboxes as you move between them! The only thing about this app i dislike are its notifications - they're quite loud compared some others out there but otherwise not too much else really apart form being able use all 3 platforms which makes life easier when working remotely or traveling often without internet access sometimes. This saves us time by letting one person manage our business email whilst another manages his own personal ones through gmail etc instead sending multiple copies back & forth via whatsapp groups we can work together more effectively than before now saving both money an resources.