I spent some time looking at a 2017 in the Carling Mazda dealership here in Ottawa and I quite liked it. My wife drives a 2016.5 GT, so I was looking at some of the changes to see what improvements were made.
Overall, the cabin seems to be finished to a slightly higher level. That said, I don't like the center stack on the 2017 and greatly prefer the stack on the ours. I love that there are hvac vents for rear passengers; that is a major let down on the 2016.5. I also really like the fact that there are usb outlets in the reaf armrest; another missing feature on my wife's car. The rear seats also have a slightly more comfortable angle to them.
The power lift gate is just something to break down the road and, interestingly, it didn't seem to have a sensor to stop its travel when there was something in the way. I stuck my arm in while closing it to see what would happen, and it just kept pushing against my hand. I had to pull pretty hard to stop its progress, so anything caught in its path is likely to get crushed. I'm not sure how this is handled on other vehicles, but I wouldn't want this feature on mine.
Visually, I like both vehicles. That new red paint is gorgeous.
Overall, I would say it is a nice improvement in a few small areas that make it a better family vehicle.
Cheers,
Jay