I have a 2017 that I've had for two years and I am at 10k miles. I have already had the airbag recall done and so far no other serious issues. I had a problem twice with my backup cam staying on for prolonged periods (I was driving around with the camera on, even going forward). The dealer said it's a software issue and they are working on a solution.
You can probably contact an Infiniti dealer about the maintenance costs -- just call and ask them about what the major service intervals are and the costs. So far, I've just had oil changes.
Otherwise, it's just getting used to some of the mildly annoying things in the basic design of the car, such as the doors that will only unlock when you push the button, seat controllers on the door, run flat tires and also pushing a button to put it in park, instead of sliding the shifter all the way forward.
Overall, I like the car. I had a 2015 Impreza Limited and this is far and away better. It has slightly smaller rear seats and cargo area, but it handles better, has far more hp and torque, it is quieter and has a nice stereo. I don't have the braking system, but everything else (premium package, nav, LED lighting package). It drives well in the snow, as well.