Michael Z Williamson is one of my favourite authors. Contact with Chaos is his fifth SF book (he has a few other non SF ones) and cements his place in my list of favourite authors. If does indeed confirm MZW as one of the authors whose books are worth rereading as they contain lots of layers of stuff to make you think.
I've reviewed two of the previous 4 (Freeholdreviewed here and The Weapon reviewed here). I probably ought to have reviewed the other two but haven't. Bad me. Contact is set in the same universe as Freehold and the Weapon (and Better to Beg Forgiveness) but it should stand on its own quite well. Now I personally think both the above books are excellent and worth reading so it won't do you any harm to read them first but don't let that stop you going out and buying this one.
[Probably all the background you need is this: Freehold (in the Baen Free Library - text linked to above) is a tale about how a libertarian/minarchist world might stack up against a much larger statist world very similar to the one we see developing on earth today. During Freehold, war breaks out and megadeaths occur before statist Earth finally agrees to peace. The Weapon covers pretty much the same time period but from a different perspective and its hero is the father of one of the characters in Contact.]
OK now back to the subject. Contact With Chaos is a "first contact with aliens" story. While the main protagonist of Contact is from the Freehold system and some of the plot threads involve how governments interact with and rein in rapacious corporations under such a minarchist system, the main point of the story is the alien culture. I'm going to try not to give away spoilers but I don't think I give anything away by stating that the major issue of the book is to determine how advanced the alien culture is.
Initially it looks like the aliens should be basically stone age because, due to a lack of meteorites and vulcanism, the planet has no metals that can be readily exploited. The interesting question therefore is to wonder how far a non metal using race can progress. Note that the metals are present, its just that they are present solely in chemical compounds and thus the intelligent species has no idea how useful they can be when present in elemental form. About the only spoiler I'm going to drop is this: you can in fact do a lot with ceramics, glasses and organic chemistry. Needless to say failing to understand this causes the humans some surprises. As another writer put it "Check your assumptions in at the door". However as the author himself points out in this Big Idea post, a lot of what we think of as "iron age" technology actually doesn't use iron or any other metal so you can go a very long way with alternatives if you don't have metal readily to hand.
One of the interesting parts of the book is how the protagonist tries to get his fellow humans to present a common face to the aliens. This, it seems to me, is very very true to life and it is a major strength of the book that we get to see the factions and disunity between the human explorers and just how bemusing this might be to an alien society which is probably slightly more regulated. The motivations of scientists, business people, diplomats, priests, journalists and so on are necessarily very different and the conflicts between their motivations allows for a a lot of interesting plot twists.
While the plot is good, and the idea better, I don't think this is necessarily his best book when it comes to the characters - perhaps because the book had to be finished up while the author was serving in the USAF in the sunny Middle East. I never really quite formed a rapport with the prime POV character and because of the way the story is told we never get inside the alien mindset which is a bit of a pity. The aliens are quite well done if you want to have not very alien aliens. We're talking a more or less avian/dinosaur/lizard sort of bipedal alien. Yes they are different but they aren't methane breathing blobs and they clearly have many of the same viewpoints of humanity. The culture(s) are different of course but recognisably similar to human ones. This is a good thing if we ever do encounter aliens because that gives us points of contact that we won't have with cultures that have no similarities.
However while the characterizations aren't perfect this is a book that like so much classic SF doesn't need strong characters to engage the reader's interest. The book fascinates on many levels and, like many another good book, leaves us wishing for more even though all the major loose ends are tied up. Given that so many authors nd their publishers seem to delight in ending on cliff hangers it is a true joy to read a basically stand alone book.