I just finished The Parasite by Neal Asher.
This was quite meaty for a novella and I really enjoyed it. It is one of Asher's earlier works, and lacks a little bit in the editing compared with the Pan/Tor novels, but that's OK because if it wasn't self re-published on Amazon it wouldn't be available at all.
In particular it was a treat to read about some early Polity tech ideas before the Polity books were written, for example, chainglass, golems, and an obsession with nano tendrils taking over a human body.
There was plenty of Asher style gore, and a high body count, much enjoyed, good fun.