I initially thought that NCIS was just another CSI clone but after watching a few episodes I became a believer - I never expected to enjoy this show as much as I have.
The episodes move at a quick pace and the cases are interesting enough to grab your attention and hold it. The writers are not afraid to let story archs develop over the season (sometimes over multiple seasons) which makes for really good character development. Threads of a mystery are initially spun and only fully developed in later episode (The Meat Puzzle, DiNozzo's undercover work are ones that comes to mind).
The characters are all different, each with their own quirks - sometimes you wonder how such a disparate group can work together but they get the job done. Also the humor that is liberally laced throughout the show adds to its charm.
7/10