If you've never been, make a promise to yourself to go, and follow through with it. If you love baseball--heck, even if you like it a little bit--you owe it to yourself to catch a game here at least once in your life. There's no better place in Boston to sit on a warm summer evening than Fenway Park, a hot dog in one hand and a beer in the other. The fans are diehard and you'll quickly make friends with them, the loud, boisterous, and usually intoxicated Fenway loyal.
Prices here are more than at any other stadium in baseball. More for concessions AND tickets. The bathrooms are gross, and there aren't that many of them. And sure, Fenway is antiquated compared to bright, shiny Petco Park, but the history is unrivaled. I'd rather be at Fenway than almost any other place in the world. Go Sox!