I've bought the individual seasons as they were released. This package is a good deal at this price, if you don't have any of the seasons already.
I don't usually watch crime dramas. My entire collection contains only 5 categories: NCIS, House, sitcoms, SF shows, things with vampires in them.
I tried CSI, Law and Order, and a few others. I was bored to tears, didn't buy them.
NCIS on the other hand is different. The acting is superb, the characters are funny and likable, and there's a lot of action and humor.
I'm currently watching these DVDs for the 4th time, and they're still very enjoyable.
You're getting a total of 138 episodes of about 40 minutes each. That's over 15 hours per season. Very few shows are that generous.
Audio and sound quality are just fine. There are English subtitles, if you want them. Probably for other languages too, but I haven't checked.
The part I like most about NCIS is how every character is interesting and gets a lot of screen time and makes you care about him or her. It's not just Mark Harmon, that is. Tony and Abby are just as important, for example. I've only seen this sort of thing in Stargate SG-1 and Buffy, and it's extremely hard to do right.