Despite the passage of time, I thought HSB stood up very well. Most of the problems discussed in the book and the techniques to find them should still work today. The targets have changed somewhat (XP was the target in the book; Windows 7 would be more helpful today -- thought not everywhere).
Again, this is an impression and not a review, so I only offer thoughts and not opinions or judgements on the text. From what I saw, the book appears well written with helpful diagrams and screen shots. It covers a lot of surface area and ways to exploit it.
One note for the history buffs: the foreword says:
When Jesse James, the famous outlaw of the American West, was asked why he robbed banks, he replied, Thats where the money is.
I'm sure most of you think that Willie Sutton said that, not Jesse James. According to Snopes neither of them said it:
While lore would have it that the bank robber replied "Because that's where the money is" to that common question, Sutton denied ever having said it. "The credit belongs to some enterprising reporter who apparently felt a need to fill out his copy," wrote Sutton in his autobiography. "I can't even remember where I first read it. It just seemed to appear one day, and then it was everywhere."
But back to the book -- should you buy it? If your job involves finding vulnerabilities in Windows software (and this book does have more of a Windows slant), I would take a close look at it.