This is a very good, and often superb, Osprey campaign titles, with very few of the glitches and typos that can mar other similar titles.
For starters, it allocates enough space to clearly present the context of the Pylos and Sphacteria campaign. For this, it goes right back to 479 BC and the victory over the Persians, before summarizing the building up of the Athenian Empire, the first clash against Sparta and its allies, the resulting peace, the growing tensions and the first years of what we know of the Peloponnesian War (the Spartans and their allies would probably have called it "the War against Athens").
The time and space taken to present both the immediate and the wider context of the campaign brings several other advantages to this title. First, it can be read as the sequel to the author's other title "Plataea 479 BC." Second, it does provide enough material to understand why the Peloponnesian War between the two great alliances of Greek cities broke out. Although it does not discuss its causes in detail, it does show that this was the second such conflict (see the section very aptly titled "The First Peloponnesian War 459-446 BC) into which Sparta was drawn because of Athenian expansionism.
Third, it presents with the first stages of the war (termed the Archidamian War, with the title borrowed from one of Donald Kagan's volumes) with sufficient detail to show the main characteristics of the conflict by the time the Pylos-Sphacteria campaign was to start. The conflict had become a bit of a stalemate, with the Spartans and their allies raising Attica every year but unable to draw Athens into a decisive land battle where the superiority of their hoplites would allow them to prevail. Athens, on the other hand, despite huge losses to the plague was predominant at sea, and laying waste to the coastal territory of its enemies, of Sparta's allies in particular.
Another quality of this title is the care taken to present the components of Athens' naval superiority, with the author having made full use of the reports on the reconstructed Olympias trireme, its performances and its remarkable manoeuvrability. It also shows the limits of these warships which were crammed, largely "fair-weather" ships and had to make for the shore almost every evening for watering, if not for food.
The events of the campaign are clearly presented, including the strategy of the Athenians and the blunders (but also the courage) of the Spartans who, with the exception of Brasidas perhaps, were clearly out of their depth (no pun intended!), wrong footed, and bested at every stage. Full use is made of Thucydides which is often (and very aptly) quoted verbatim. The author is careful to show, however, that the campaign was not as one-sided as it is commonly believed to be, as the Athenians faced huge issues to supply their expeditionary force with food and water.
The title also includes a number of helpful maps, photos and plates that support the main text rather well. The four plates - the Spartan attack from the sea (where Brasidas was wounded), the Battle of the Harbour and the two showing the Battle of the Island - illustrate rather vividly the Spartan predicament. The bibliography is also quite good, although it might have been preferable to list Donald Kagan's four volumes on the Peloponnesian War (and, in particular, the one titled "The Archidamean War" which deals specifically with this period of the conflict and with the Pylos-Sphacteria campaign) rather than his one-volume summary. Another little glitch - clearly a typo - can be found in the chronology, where the dates for the disastrous Sicilian expedition of the Athenians are wrong (it took place 415-413 BC and not 417-415, as indicated).
One point that is a bit controversial is the interpretation according to which hoplites and Spartan ones in particular, started to fight without body armour and increasingly discarding it. The author and the illustrator have chosen to show them without such armour, not even leather, as early as 425 BC, making a case that this was a deliberate response to the increasing threat posed by specialised light infantry (archers and peltasts in particular). The Spartans did select some of their younger and faster hoplites (called ekdromoi, but also epilektoi if I remember correctly) and train them specifically to fight without body armour and sprint out of the phalanx to catch light infantry. It is however much less certain that the lack of body armour was as generalised as shown in the plates and mentioned in the text.
Finally, the title also addresses the aftermath of the campaign rather well. In particular, it shows to what length the Spartans were ready to go to get back their Spartiates prisoners. It also shows that the campaign was indeed a disaster for Sparta, at least in terms of reputation, although the Athenians, by refusing peace terms immediately after their victories, when they clearly had the upper hand, squandered in part the benefits of this campaign, allowing Brasidas to somewhat restore the balance by his own victories in Thrace.
Five stars for a rather superb title.