Wow I've never seen a more praised car on car-survey, and my comment won't make any difference because like others, I think the J30 is a great car.
I am privileged to own a 1997 J30t; the final year they were made, and of course the top of the line touring edition.
What's good about the J30 is that it is solidly built. If you get in an accident, there's a huge likely-hood that the other car will suffer greater damage. The interior has a cabin-like feel to it... you just feel safe.
Another thing is that they are very reliable cars. Personally for me I think they could be a little more refine as far as engine smoothness, off the line acceleration, and quietness. You will notice a significant driving performance difference between any model/year Maximas 1990 or later and the J30, with the Maxima having a competitive edge, but that's apart from the point.
The J30s are great sedans with a unique styling that never seem to age. However, I would agree with all comments indicating that they are extremely expensive to maintain, especially when it comes to buying parts and performing the services, because they are very technical and specially made.
I would recommend this car to anyone buying a car, and I'm not associated with Nissan in anyway.