Hello Nancy,
I like her physique because while she is thin she is not anorexic and lacking energy: Jari uses 8lb dumbbells and 10lbs for the workouts and she does all the exercises in S&L as opposed to other members of her crew who uses less (I haven't tried her workouts using the same weights as her yet so I am not sure how strenuous they are). And she has great muscle definition as well. She reminds me of Bruce Lee and Paula Radcliffe, two people who are very very fit and slim. I like her body because I don't believe that you are unhealthy if you are underweight: in fact when people are doing a very physical job they tend to be very thin because you burn so much calories. I have been in that situation when I used to cycle a lot.
I would agree with everyone who say that Jari looks too thin and that was my first impression when I saw her DVD cover. However, in Get Ripped I thought she looked lovely, quite feminine and slimmer than her crew, but she doesn't look like she would collapse. In S&L she is more muscular but not necessary slimmer (at least I don't think so).
I did read somewhere that it is healthier to be a little under your ideal weight.
While Jari is thin she is definitely not in the same category as all those celebrities who are size 00, like Nicole Richie, Victoria Beckham and Kate Bosworth. There is definitely something wrong with those women.
I don't mind being thin as long as I am fit and healthy (that is the most important).
Yen