I liked the older Maxima, but the new one is just hideous to me. Nissan's 3.5 V6 is a very nice engine, however, and in the Altima, it feels very torquey.
In terms of value, though, the Maxima is just not a contender. If I chose a Japanese car, I'd be MUCH more inclined toward the Acura TL. I recommended a TL to a friend late last year (the 300 wasn't available and it wasn't on my radar).
I still think the TL is an excellent car, but the driving experience is a bit sterile. It is such a well-built car and the interior is lovely, however, it just didn't EXCITE me. The bellow of the 300's V8 makes me tingle and the visual impression of the car is unmistakeable... nobody will confuse it for an Accord!
The Maxima is just not a good value by comparison to the 300. If you HAD to buy a Japanese car, there are several others I would pick first.
Personally, I can't wait to be behind the wheel of a V8 car again. My car is scheduled to be built in four days, and will arrive sometime next week.