I tend to give Stross' work 5 stars by default and then subtract from there. The Rhesus Chart, unfortunately, is sufficiently uneven that the 4 stars I do give it is a little bit generous and subjective. I love the book, as I pretty much love everything Stross bothers putting to paper, but objectively this is among his weaker efforts in pure technical terms.
Its weakest aspect is, ironically, the central storytelling conceit: Bob Howard's narration. Where this has been a strength in previous books—Howard's quirky personality and outsider's perspective are what actually makes the Laundry universe work—here Stross stumbles at times.
At several points (principally where Stross' narrator reaches for movie tropes and similar for summation) the fourth wall is broken in a way that takes you out of the story (even in first person prose, if the narrator too directly addresses the audience it breaks the suspension of disbelief). Worse still, these instances tend to be points at which Stross for some reason feels the need to have Howard sum up the state of the story so far. If these had been summations of the story from previous installments I might have understood it (not enjoyed it, perhaps, but understood it), but here he just sums up the previous chapter or two. It comes across as either filler or a somewhat insulting assumption that his audience can't keep up with the plot developments they've just been shown and have to be told what's going on.
The situation isn't exactly improved when what should by all rights be the climax of the story, Stross' narrator resorts to quoting a bureaucratic “after-action” report. Fair enough that Stross' narrator is neither omniscient nor present at the events in question, but this holds true as well for the first third or so of the book where Howard has no trouble dramatizing the events preceding the point where he first intersects the plot. The net effect is that a development that should be the climactic scene in this book, and fairly huge for the series and the Laundry universe as a whole, reads drily and perfunctory. This should have been swimming in pathos, and instead it barely managed to rise to the level of holding my interest.
This of course compounds the fact that what is then left as the actual climax of the story—not least because this is the event which our narrator, Howard, is directly involved in—is written more as the penultimate challenge, the final set of minions before the boss fight. The combined effect is one of anti-climax and skews dangerously close to bathos when it comes time to exhibit the consequences.
There are also some annoying plot holes, the worst for me being that directly contradictory information is given about the state of a major character's fate in a way that undermines the tension that either possible outcome would have provided. These are annoying, but, I suspect, mostly reflect too much hurry during the writing and editing, and are overall minor sins (for instance, a commenter on Stross' blog pointed out that the timeline currently leads to a minor character being pregnant for 11 months).
Overall I'm left with a suspicion that here we see the scaffolding poking through. I wouldn't be at all surprised if I were to learn that Stross signed a deal for a number of new books in the series of which this was the first, or that someone (his agent, publisher, or his own commercial acumen) pressured him to make this a good jumping-on point for new readers (which, if nothing else, would explain the incessant summation). It also seems obvious to me (which is usually the surest sign that I'm wrong, but still...) that Stross is here attempting a pivot (see what I did there?), of sorts, for the series. Everywhere the plot felt disjointed could be easily explained by Stross' hand trying to retcon and shift his characters and the universe into a subtly different direction to fit with his plans for the next three books. There are developments in Howard's personal life, telegraphed early in the book, that make sense mostly to supply a source of tension for future books. A character is introduced (possibly intended as a deliberate red herring) that probably will play no role for several books, but which take up disproportionate space in this book for no good reason. Another character is reintroduced with a completely different personality than previously, and then goes on to exhibit such markedly divergent traits as to leave the overall impression as pure schizophrenia (and to be clear, I'm implying that Stross either failed to reconcile different sides to this character, or simply changed his mind while writing and insufficiently corrected previous prose). Who exactly constitutes the main villain isn't exactly clear; there are several of them and despite enormous buildup, by the end of the book you can't help but feel they're actually all kinda pathetic.
Now, apparently the next book in the series will be narrated by Mo and will overlap with The Rhesus Chart, so possibly Stross had half an eye on that and the further books, but overall I'm just plain disappointed by this showing. There's no doubt Stross is a better author than what's on show here, and I had so been looking forward to that book.
That all being said, even Stross half-assing it and phoning it in is better than most of his peers on their best showing. While the scaffolding may show through, the remodel Stross seems to be attempting here is both necessary, timely, and makes me excited for future books in the Laundry universe. The plot may be a bit thin and strained at times, but Howard as a narrator is amusing as hell and draws you safely by thrills and horrors both. And ultimately, more of Stross' unique vision and imagination is worthwhile no matter its wrapping.
I love Stross' writing in general, and especially The Laundry Files, and that includes this particular ugly duckling. Not, contrary to apparent intent, the best place for new readers to get onboard (I still recommend The Atrocity Archive for that), but for existing followers of Agent HOWARD's exploits, more Laundry can only be a good thing.