Silverfin is part of the Young Bond series, charting the escapades of Bond before he realised his true path. The format (being a graphic novel) works extremely well with the story, as the more filmic elements can be easily portrayed and it lends itself to some of the more gruesome elements in the tale. It also helps mirror the films in that the dialogue typically isn't the central focus, giving way to effects and setting which works equally well in this medium.
While these are it's merits, I found some of it a little laboured; too much exposition on the Eton setting and relationships, when more punch could have been put into the plot development later on. It was definitely seeming like a slow burner with the main events playing out very fast in comparison.
It would be suitable for KS2 pupils, and could be a good route in for those that are more reluctant readers given that it is not so text-rich. It could also be used to explore different mediums and their merits, inviting comparison between stories or even film.