Okay, the reason this is a “first impressions” post and not an actual review is because I absolutely suck at judging mechanics in the abstract. Is the army going to be better or worse on the tabletop? I have no bloody clue, I just can't work out the numbers in my head. Until I see something on the tabletop I find it hard to judge its value.
One thing I will say about the rules in this codex is that the bespoke force organisation chart is insane. It isn't the usual slightly tweaked force organisation chart (such as Orks having nine Troops choices and Blood Angels having four Elites) but a chart made out of formations. You take a Reclamation Legion formation (an Overlord 0-2 Lychguard units, 1-4 Immortals units), 2-8 Necron Warriors units, 1-3 Tomb Blades units and 0-3 Monoliths) and then add on a selection of up to eleven other formations. Its a wonderfully characterful representation of how Necrons fight en masse, analogous to a Space Marine chapter, but the size of even the smallest force means its probably of limited use to the casual gamer.
Honestly, this feels more like a background resource than something meant to be used in normal games.
The Warlord Traits are the usual mix of character buffs and army buffs, the one I'd hope for being Hyperlogical Strategist which allows you to add or subtract 1 to reserve rolls and seizing the initiative.
Reanimation Protocols are less annoying than when I last faced Necrons under their 3rd edition rules. Now its a slightly modified invulnerable save taken after suffering an unsaved wound regardless of circumstances (Instant Death doesn't knock it out, merely lowers it to 6+ from 5+).
Honestly, what interests me the most is the background section. As well as showcasing artwork in styles I haven't seen in GW publications before it resurrects the bestiary section that has been so absent from recent Codices. This is probably because Necrons are a less well-defined army in the minds of gamers than Orks of the many Space Marine factions so there are sections describing how Destroyers, Immortals and so on fight and what their origins are. There are also these cool technical drawings that remind me of Imperial Armour books and 4th edition army lists which had a drawing of the thing next to their entry.
Sadly, there isn't as much background dedicated to the Dynasties as I'd like. A few of the pre-existing ones are given brief focus sections that expand on their background but several interesting ones are cut, only to be mentioned in the map and timeline. Speaking just for myself I'd have loved to read more about the Empire Of The Severed or (I can't remember the name) the Dynasty that some exiled Lordling reprogrammed to obey only him and turned them all into his personal pirate empire.
Personal issues aside this is a great looking book. As I said they've really spread out into differing art styles I wouldn;t usually associate with a Codex. The map in particular is great and very much drawn from the Necron point of view with their dynastic territories picked out with Imperial worlds only included as points of reference for the reader. Production values on this one outstrip the Blood Angels book, in my opinion, so its a pity this might be the last Codex for a while since it seems a bit soon to launch into a new cycle after two and a half years.