Trilogy endings are usually where a writer’s honest intentions meet the requirement to put everything back. Zahn mostly refuses. The Last Command resolves the Thrawn campaign without restoring the status quo, and it ends on a decision by a minor character that the previous two books quietly earned.
What it has to close
Three things: the cloning operation at Mount Tantiss, the campaign for the Core, and the question of what Mara Jade actually intends to do. It gets through all three in under five hundred pages without any of them feeling rushed, largely because Zahn spends the first act narrowing the board rather than widening it.
The ending
Thrawn is not defeated by strategy. He is killed by his Noghri bodyguard, Rukh, because the thing he never audited was whether his own house was loyal — and the Noghri have spent two books discovering that the Empire lied to them about their homeworld. It is the correct ending for this character, and it is set up so far in advance that first-time readers rarely see it coming and second-time readers cannot believe they missed it.
It is also, structurally, quite hard on the heroes. They do not beat him. They survive him.
Mara and the Luuke problem
The Mount Tantiss material produces a clone of Luke Skywalker, and the book insists on calling it Luuke, which is the single silliest decision in the trilogy. Set the name aside and the sequence works: Mara Jade fulfils the Emperor’s last command by killing a Luke Skywalker, which is exactly the kind of technically-satisfied oath that lets a character walk free of it. Zahn has been building to that release since her first scene.
Craft
The fleet action at Bilbringi is the best-run space battle in Legends fiction — legible, consequential, and built out of decisions rather than firepower. Against that, the prose is still workmanlike, C’baoth’s ending is operatic in a way the rest of the book is not, and there are a couple of coincidences in the middle third that a tighter draft would have removed.
Why it mattered
It reached number one on the New York Times bestseller list, which is the practical reason the Star Wars publishing programme existed for the next twenty years in the shape it did. Read the trilogy as a whole and the achievement is clearer: three novels that took a franchise everyone assumed was finished and demonstrated there was a working, profitable, ongoing story in it.
Who should read it
Anyone who has read the first two. Do not start here. And do not expect the sequels the Expanded Universe built on top of it to hit this cleanly — most of them do not.