Not the stories and scripting, which are fine but pedestrian, with one exception: the presence of actual wit. The opportunity given to Mark Harmon to have a twinkle in his eye. The nerd relationship, which while totally hackneyed, hasn't driven me crazy yet. Mark Harmon's coy silences, which remind me of British TV. Bravo for silence and a knowing glance!
The real star of the show is the direction. Comparing the direction of NCIS to the Law and Orders and the CSI's is like comparing 24 to The West Wing.
On NCIS, the camera darts here and there, and the editing is superb. Everything comes to life and the entertainment value is heightened because of the directorial, and therefore editing, style.
If you're a Law and Order fan, look at NCIS, and give your eyes some exercise. It's so terribly boring watching people just stand there and talk.
Meanwhile, I've joined the Navy.