It's of no surprise that even in their own book, the Tau get the amphetamine parrot kicked out of them by the Guard.
This is only a novelette and not a full novel nor is this a review of the novelette compared to discussion of its contents.
The book is primarily focused on Shadowsun after her ship is shot out of the sky by an Imperial defence laser from an Imperial planet being annexed by the Empire. Shadowsun escapes in a solo pod while a Manta also manages to get away before discovering a sub-optimal intersection of the air-earth interface. The survivors of the Manta crash and Shadowsun have to find a way to disable the defence laser before any of the remaining Tau fleet can come to their rescue let alone continue to conquer the planet. Meanwhile, the local Guard garrison is less than impressed with the whole invasion thing and are taking it rather personally.
Of note - the Tau now have FTL communication abilities not relying on courier drones or vessels.
The Greater Good still used messenger drones (size of a torpedo basically) so there is a progression away from the former small spaceships required previously. The approximate range of 150 light years or so allowed communication in hours to a day delay. So obviously not instantaneously but far better than previous options.
Even a Manta contains the required equipment to communicate over interstellar distances.Tau still use cryo sleep for their vessels on long journeys. Shadowsun mentions she'd lost two and a half years of time during the recent journey.
Shadowsun had two sisters. One died at Medusa IIRC and the other is stated as being killed by Dark Eldar.
Tau have a
Sole Survivor Policy where the remaining member of the family may honourably withdraw from combat duties and return to their Sept world to raise a family. It still appears your family mate is matched for you rather than by choice but no real detail is gone into as, understandably, Shadowsun isn't all that fore coming in discussing it.
Shadowsun's command drone is capable of communicating to ships in orbit as well as on a more global scale. Light minute distances were right out though.
Air caste ship commanders of rank are DNI into their ships and have hard wired displays attached to their eyes.
A Tau escape pod contained not only Shadowsun but also her armour and weapons in separate compartments. The Air Caste AI within the escape pod can also be put into a
blue screen of death by having it being forced to choose between two equally conflicting priorities. Fire Caste AI is a lot more direct and no bullamphetamine parrot as you'd expect. Maybe VI is a better term as no real discussion of range or capability is given.
Aun'va is still kicking around. He's also still wearing a very big silly hat.
Tau lifespans are still short. Shadowsun mentions being in in battle for 20 years and that being half her potential lifespan.
Fire warrior armour is fully environmental. Wander through a forest fire, no worries.
Tau blood is blue. This is mentioned a lot. See the first sentence at top.
Tau are getting more obviously oriental in approach. For instance, Shadowsun found a commander surrendering after defeat of their men to be dishonourable. Filthy barbarians, such as the Guard major, were also not to speak to Shadowsun directly and had to use a lower ranked Tau to talk to first.
Shadowsun's battlesuit can take a whole lot of amphetamine parrot even without her shield drones (which she lost a *lot*). Even so, massed lasgun fire hurt her a lot.
At books end the Tau still conquer the world even after the amphetamine parrot storm getting there and a whole two Tau survivors from the start.