General Image Quality

The NEC 2490 sets up highest image quality standards in the industry.
High contrast ratio H-IPS panel with calibratable LUT, combined with A-TW polarizer leaves no chances to its competitors. The closest one (2690WUXi) is from the same stable, but it has wide color gamut. Wide color gamut is beneficial for a particular part of professional users (1%? of all users). But we belong to the 99% of users for whom wide color gamut issue is just irritating.

In addition to its unique panel, 2490 has various convenience features and qualities. Some of them have been mentioned above in this review. Some will be overviewed below.

Viewing angles
A monitor can have excellent measured values even out of box: formally accurate colors and deep black. But that is on paper.
When it comes to reality, viewing angles decide what is good and what is not.

TN monitors
For these monitors good measured values, of course, are desirable but they mean little. TN panels suffer from severe angle color shifting, especially vertical color shifting.
Colors on a TN panel are never evenly distributed regardless the point of view.