The Hammer is formulaic. It's a very effective formula, and one that has made me a fan of KJ Parker's work, but it's a formula nonetheless. You'll find here the same characters and tropes that inhabit most of Parker's other work: good characters that turn bad, bad characters that turn good, a seemingly relentless logic that leads to extreme and brutal results, and, most of all, a metaphor hammered until it's paper thin, then folded and re-folded and hammered again.
You'll find, also, the common vocabulary and the usual tantalizing hints that all Parker's work occurs in the same world. There is a Company, a Republic, and Empire, a Colony. In this case, there is an explicit link to other books in mention of the Vesani Republic.
I like KJ Parker. I really do. I thought the first Parker book I read (Colours in the Steel) was excellent - despite what was then unexpected savagery. I liked other series almost as much, but felt they weren't treading very far afield. Recent standalone books continued the trend, though The Company at least offered a different setting.
The Hammer sticks very close to the approach Parker has perfected. So much so, in fact, that it feels like a book she (let's say) has written before. If you've read Parker's other work, you've pretty much read this one. You know what will happen. You know where it will end. Only the details are different, and in this case, they're just not that interesting. It feels like something off a production line. That's a shame, particularly from an author whose approach and tone are so different from those of most other fantasy authors.
I'd be very disappointed to find that Parker has only one string to her bow. I'd still read her books, much as I still read Stephen Donaldson's books. But I'd hope for more.