I have the kit on my '91 and have done a lot of posts about it, but will try to organize those random tidbits into a more coherent discourse.
First the negatives. It is heavy. Probably adds a couple of hundred pounds to the car, so don't install unless you are willing to give up a tenth or so or have a modified drive train. I have a heavily modified motor and feel the extra traction I get from the wide tires more than offsets the weight increase.
Second, it really is a body kit, not just some bolt-on rocker panels and a front air dam, so it is a major undertaking. You will be replacing all four quarter panels, the front and rear bumpers and the rear wing. If you want it, find a good custom shop with lots of fiberglass experience.
Now the good news. First, it looks incredible. This is what the car should have looked like from the factory. It really transforms it from a sports car to an exotic, but in a very nicely designed way. It is not 'ricey' at all like the JDM 'boy racer' looking kits. It was designed by someone from the Honda SoCal design studio, who presented it to Honda Japan as an evolution/update for the NSX. They declined (production numbers too low to bother to retool). So, he offered the design to Comptech, because of their close realtionship with Honda.
To give you some idea of the visual impact of the car, mine is in Bob Norwood's shop next to Testarossas, an F40 and an F50 and visitors routinely walk by the Italian cars to stare at mine. It is hard to really appreciate how pretty the new body is until you see it in person.
It will allow you to go to substantially larger tires and wheels. I have 18x12 wheels in the rear with 335s. To put that in perspective, that is the same rear tire/wheel size on the Viper.
I am very happy with mine and have no regrets whatsoever. When I see a stock NSX now, it looks a bit puny to me.