Sly Mongoose is set several generations after Ragamuffin, and our old friend Pepper is back in the middle of the latest crisis. As always the alien machinery inside of him has caused him to outlast and outlive everyone around him, so he's the only character you'll remember from previous books. The descendants of the Azteca fled New Anegada and their alien masters, and now live in floating cities set about a deadly planet called Chilo.
One of the things I love about Buckell's work is that his books in this series have enough similarity of style, exploration, themes, etc. (not to mention the fantastic character of Pepper!) to satisfy someone who's looking for more of 'the same'. However, each one is also quite different from the previous books, so you certainly won't feel bored with the material! Each book takes place some time after the previous one, in this case several generations later. Each book explores a different part of the universe, although at the same time it takes on the consequences of previous plots. So there's a ton of new material while also a few familiar threads to hold onto. This also means that the books can stand alone, although you'll have an easier time following some things if you know what came before.
The characters are complex and interesting. As usual it could be argued that Pepper is actually not the main character, although perhaps he is more so in Sly Mongoose than in the last two books. This is a great approach, because Pepper's certainly not your standard hero, nor even your standard anti-hero, and it's often both useful and important to see events through other people's eyes as well.
In many ways Buckell's books hearken back to an earlier style of hard SF that drops you straight into highly alien situations and lets you absorb it all, rather than starting from something familiar. They also contain a strong element of exploration with regard to alien sentience, societal and governmental structures, and so on. Most refreshingly, he explores all sorts of positive and negative aspects of these things without holding up a sharp agenda. It's writing that makes you think, not writing that preaches. He also writes with an incredibly unique flavor that I've not seen in any other author's books, so if you're looking for something new, his books are a great bet!