Cute little airport on the Toronto waterfront.
The ferry departs every 15 minutes and is only a 1 minute ride to the island airport. A new pedestrian tunnel is opening up soon so I assume ferry service will become less frequent (for vehicles mostly).
Most flights belong to Porter and you'll have access to the Porter lounge which is simply amazing. Feels like you're travelling in business class when you have access to free drinks and snacks.
Finally, check in and security is a really quick process. Coupled with the convenient downtown location and it's a big win for travellers.