The only thing better than my M45, was the M45X I purchased, then along came the M56X - I got one of the first in the region. Nissan really listened when they built this. Everything has improved, and the additional horsepower puts it into a different league. I love the ride - feels more substantial, and corners like it's on rails with breathtaking acceleration. My wife says it reminds her of our BMW 750 - but more fun, with a sexier interior and exterior. Electronics, back up cam, sound system, etc. all exceptional. They even added a heated steering wheel and retractable outside mirrors. The dial-a-transmission is very clever. Bravo!
Looks, reminds me a bit of the Maserati Quattroporte - photos don't do it justice. Power. Sound system. Handling. CD Storage capacity. Controls that allow access to electronics via touchscreen, console or on steering wheel.
I haven't run into anything yet as it's too new. Loaded a CD into memory that it didn't tag with a name, but think that is because it was home brew disk.