The biggest mistake people usually make is to call NCIS yet another procedural show. And while solving crimes is a big part of the show, unlike CSI clones, NCIS is all about the characters. Their interactions and chemistry is really what keeps the show going. And no matter how picky you are, you will be fascinated by the dynamics and you'll find yourself in love with at least one of main characters.
The leader of the group and at the same time the most charismatic person is Special Agent Jethro Gibbs, played by Mark Harmon. He's a former Marine who lives by his own rules and is building a boat in his basement (for years fans wondered how on Earth is he going to get that boat out of said basement). Gibbs is in fact the main focus of the show. Over the course of the 5 seasons (as of 2008 the sixth season is in production) we learn his background, history of failed marriages and his tendency to hold conferences in the elevator.
The most colorful of the character is by far NCIS forensic expert Abby Sciuto played by Pauley Perette. This Goth with numerous tattoos and a caffeine addiction is the most energetic of all the characters we're introduced to. She brings the life to the team, often bringing a different perspective as well. Her father-daughter relationship with Gibbs not only shows us that the tough Marine has a gentler side to him, but also gives us the more childish side to the very competent forensic specialist.
Gibbs' senior field agent, Agent Anthony DiNozzo (incredible performance by Michael Weatherly), feels like the most complex character of the bunch. On the outside he's a typical playboy. Coming from a rich family, he talks only of expensive clothes and his numerous conquests. But with each story act the writers show us new sides to Tony DiNozzo, making us realize how much he loves his job and how much Gibbs' approval matters to him.
In a matter of character development, I really enjoyed Agent Timothy McGee's journey. From a geek who second-guesses his actions to a confident NCIS field agent capable of not only hacking the most complicated systems, but also performing a security detail and catching the bad guys.
Those I have to say are four of my favorites characters. Others that deserve to be mentioned are Agent Kate Todd (Sasha Alexander), who was part of the team during NCIS first two seasons; Officer Ziva David (Cote de Pablo) who replaced Todd during the third season and the ME Ducky' Mallard. All three of them are fascinating characters, each bringing something fresh to the show. Both Kate and Ziva have a great chemistry with DiNozzo and Ducky is easily lovable for all his quirks and anecdotes.
But aside from the strong cast and the storytelling that is heavy on character interactions, NCIS pays great attention to details as well. Their crime mysteries are often complex and well written. With plot twists one expects from a show of that quality. But I am pleased to be able to say that during NCIS long run I could say with honesty "I didn't see that one coming" on great number of occasions.
NCIS keeps you guessing, the plot of each episode is well paced and I could never say that the time I spent watching NCIS was wasted.