jbuck's experience is dated, or perhaps related to BOOST. There are no such things as Marine DI's involved with NSI, at least with the non-BOOST NSI class of 2009.
The PT regime was certainly not a joke. It was significantly different from what my ship had done. My ship focused on running, with less attention paid to push-ups, et al., but NSI PT seemed to have no specific focus in area of training. The emphasis was on form, meaning if you cannot do, say, 60 "correct" push-ups, you better work on it. The most challenging PT was when they had the only SEAL candidate run "SEAL PT" for a day. I'm sure it was probably a bit watered down, but none of the Athletic-O's could finish, so yeah...
However, the real emphasis for NSI was placed on classes. Several PT's were cancelled in lieu of study time, etc. Fortunately, they have some pretty decent gym facilities there.
One last word of advice: If you happen to run into some Heineken girls in Newport, ask for Lindsey.