I have owned a 2015 Mirage ES for the past two years. I have had zero troubles and it has been an excellent car. This past weekend I traded it in for a new 2017 Mirage SE. I opted for the same color and thought it would be the exact same driving experience. Boy was I wrong. I know the new model has 4 more horsepower and a modified suspension system, but it really is a totally different feel to drive. Below are my observations thus far. I hope they help someone that may be pondering a 2017 Mirage:
Power: The 2017 isn't a race car, but it easily pulls the hill beside my driveway with no problem and minimal throttle. The 2015 required quite a bit of throttle to pull the same hill.
Suspension: It corners noticeably better than the 2015 Mirage and is without the feeling like you're leaning around turns. The floaty suspension on the 15 made it great over bumps, and the 17 feels slightly more stiff, yet still somehow engineered to have the same softness when on a rough road.
Stereo: My 2015 Mirage had the standard stereo system. It worked well for my non-audiophile purposes. The new system has the touchscreen interface and Apple Carplay. Works great with my iPhone, but i'm curious as to why there is a GPS module sitting on top of my dash, but that option is greyed out on the display. I contacted Mitsubishi and they said Carplay supersedes the base navigation and disables it in favor of the iPhone navigation. Speakers sound exactly the same.
Bluetooth: I actually like the bluetooth integration on the 2015 better. I was able to use the steering wheel controls. On the 2017 the steering wheel controls are present, but dialing from them is disabled in favor of using the touchscreen unless I have my iPhone physically plugged into the USB port in the car. I also liked the microphone placement in the 2015 better. It was overhead mounted into the headliner. The 2017 has the microphone stuck with mounting tape/clip on the steering column. I don't expect any issues with this, but it doesn't look as nice as in the 2015. it looks like an aftermarket upgrade instead of a factory option.
Interior: I love the new look. The seats look and feel nicer. The material doesn't look as cheap as the 2015 and feels like it will be more durable (though I never had issues with the material in the 2015). The piano black trim really makes the interior look more exotic, but piano black is nearly impossible to clean without microfine swirls and scratches, so I doubt it will look so nice for too long. I also like the new chrome trim on the speedo and the new contrast. A nicely upgraded interior, but it still has the same dash and door panels. I have no problem with that...they're super durable! I would have liked an option for two-tone door panels like the G4 Mirage has.
Windshield. While physically the same size and layout, it now has a shaded area around the mirror mounting point that acts as a sun shade. Trivial, but this small detail makes the car seem less like a bottom-end car and more like what is normally seen in vehicles.
Wheels: Same Ensave tires as before, but with new rims. I had no problem with the rims on the 2015, but the 2017 SE rims are a very nice look for the car. I consider this an upgrade.
Overall exterior: Initially I didn't like the new front end in pictures, but it has really grown on me. After looking at it in person it is most certainly more refined and looks more modern. The hood now has ridges that give it a slightly more aggressive look. Around back, I love the new rear tail lights and their LED layout. They also protrude slightly from the body which gives a slightly sportier look. The rear bumper changes actually made the car look wider when sitting beside a 2014-15 and viewed straight-on from the rear. It's a great optical illusion created through design, and it totally works. The mud flaps are now black instead of painted to match the body color like on the 2015. They also feel more flexible and less prone to breakage. I never had a problem with the flaps on the 2015, but I know people that broke them more than once, so I'm sure the new softer material is the reason for that and also the reason for the molded black color without paint.
Braking: I read that the brake size was increased on this new model. I'm not certain if this is true or not, but I can say that the brakes are most certainly stronger and the car stops with less force applied.
Final verdict: Great update by Mitsubishi and well worth the upgrade! I'm absolutely thrilled with the new 2017 Mitsubishi Mirage SE and feel that it is a great evolution of the (2014-15) Mirage.