This book has been written about so much and in such insane depth that I'm afraid to even say anything about it for fear that it might turn out to be the scientific consensus that whatever event or character I describe didn't actually exist in the book. But, it's a classic and it's a very entertaining book to read. Don't fear if it ever turns out that you have to read it, or your girlfriend is obsessed with it and demands that you read it or something. In most editions you read, unless you are a native French speaker and lived in the 19th century, you will spend quite some time checking the endnotes for all of the references Stendhal made/is believed to have made. But you'll get over that.
I read the author's introduction after finishing the book, and the obsessive dissection of this book by critics and other egg heads reminds me of theoretical astrophysics and the Final Fantasy VII message boards of GameFAQs.com. For people who don't know what I'm talking about, pretend I just said a Star-Trek convention.
Saying it's a good book on the internet is kind of like going up to a painting in the Louvre and saying, "Yep, that's Jesus all right" while a bunch of snooty art critics with monocles and pointy moustaches are peering over your shoulder.