I have had my M35x for a month now. I have no major grievances, however here is my endless list of niggly little things I found:
-Steering wheel controls poorly designed. LHS up/down switch is way too easy to hit inadvertenly. Let's replay that song again!!
-Passenger seat angle does not enable support of legs of average sized person. Cannot change angle.
-Driver's seat cushion is a little short.
-I am 6' 3". I am unable to put view guages properly with steering wheel in comforable position.
-Automatic mirror-down function doesn't work with mirror selector switch in middle position (OK, I am really pushing it here...).
-Having to push the "mode" p/b four times to get the heating system blowing on windshield and feet.
Things I like:
-Back seat room.
-Front seat headroom.
-Intelligent key (I like this a lot!).
-Backup camera system.
-AWD (with Blizzak LM15's) provides very confident winter driving.
-Aluminum hood, doors and trunk will resist corrosion.
-I can it serviced at my Nissan dealer (no Infiniti dealer around).
-Headrests comfortable without restricting rear vision (unlike my Subaru).
-Has the ground clearance to handle really lousy, snow covered roads.
I like the fact that the car is somewhat invisible. It is luxurious on the inside without being to jazzy on the outside. It doesn't draw attention - good or bad depending on your viewpoint.