No specific spoilers, but a little is given away.
First and foremost: **Jarhead ** met my most basic expectations and needs- hot, sweaty, nude (oh yes!) Marines. I went in hoping for, at best, topless and sweaty Marines; my expectations were met and even exceeded. There were topless Marines (a whole bunch, all the time), bottomless Marines, sweaty (nude) Marines, and hot Marine Corps shower scenes. There were also many other good (GOOD!) times, including (but not limited to): Marine masturbation and a “Field Fuck” (which was actually a little more bizzare than sexy-- who am I kidding? It was sexy). Oh and penis ensued–many times. Almost more times than I was comfortable with-- what? I said almost!
And now that I’m done with being a giant whore for the Corps (for the moment), on to the actual content and such. First, I was pleasantly surprised that the movie didn’t try to make (too many) bold, political statements. Before I went in, I had heard from those that actually read the book that Swofford had quite the ax to grind. There were a few comments here and there about how it was all for oil, but you weren’t beat over the head with a message.
Anyone who goes into this movie expecting a war movie is going to be rather disappointed. Then again, some might say that anyone who went into Operation Desert Shield and Operation Desert Storm and expected a “real war” were rather disappointed as well. But hey- **Jarhead ** portrayed the reality of the Gulf War pretty well.
The acting was surprisingly good. I loathe Jamie Foxx, but I really enjoyed his performance here. Foxx’s character- who loves the Corps (“I. Love. This. Job. Ooorah.”) for what it has given him serves as a wonderful contrast to some of the characters who simply do not want to be there. People who “got lost on the way to college,” people who had degrees in literature from top universities, convicts, and lost souls- the movie shows a little of everybody.
Yes, the beginning was very reminiscent of Full Metal Jacket, but I imagine that any movie that attempts to accurately portray Marine boot camp will resemble Full Metal Jacket.
All in all, good movie. Good actors, interesting and different take on the stereotypical “war movie”, interesting historical perspective, good pacing (I didn’t even realize how long the movie was going), and hot, sweaty, naked Marines.
I said it before (in my infinite wisdom): “There is no way this movie could be bad.” I was right. Being the history nerd I am (particularly being a history nerd who is totally interested in the first Gulf War at the moment), I was totally entertained. Being the bleeding heart liberal that I am, I was interested by subtle commentary and messages about war that were given. Being a red-blooded American female, I was *very * interested by the shower scenes. 
Yeah, I’m gunna go now and, um, study the Bible? Yeah, that’s the ticket.