For those who have seen the Berserk television series, very little of the manga so far released has been much of a surprise. This, by no means, is a slight against the original author's work, just a testament to how closely the anime's producers followed the rich story.
Volume #6's events may already familiar to fans of the series, but just because they know what is going to happen, doesn't mean it loses its thrill. On the contrary, as I saw events beginning to converge on the climax I knew from the series, I began to get even more interested. The best episodes were those of the last half. The attempted assasination on Griffith, Guts' own assasination assignment, Griffith's courting of the Princess, and Casca's growing connection to Guts are all pivotal to the story.
There's a particular scene in the final chapters of the book when Guts is forced to take some liberties in order to save Casca's life that awakens him to her vulnerabilities. In turn, Casca finds her own piece of mind by confiding in him why she joined the Band of the Hawk.
Most of Guts' growth as a character is seen through action. The man isn't much of a thinker and understanding his quest for purpose (and, then, vengence) is dependent mainly on the reader's observations of the actions of Guts and those he cares for. To finally get some introspective thought from the man adds much to the overall picture of his life.
All in all, a great book... a great series, but be prepared. In the next few volumes, things will come to a head. Men will die, characters you've grown to love may pay the ultimate price, and before one man can ascend to heights unimagined, great tragedy must befall him and those around him.