Well, I got to the end of UVG after taking a break to work through a huge Economist backlog that the wife was threatening to throw in the recycle bin (I am now even more sinophobic and Keynesian than I was before; ah sweet, sweet, moderate neo-liberal propaganda...). Reading this book right before bed brought on some absolutely spectacular dreams. I have to say UVG was a real trip and a very fun book to read. I'd love to run it some day.
Though it did present the author's own OSR-style rules-light D&D mod, this was definitely an adventure product in the Sandbox category. The idea being to build a caravan and plan a route across the increasingly weird plains to a Black City at the edge of reality. It is some straight up '70's Metal Hurlant, acid-trip shit evoking all my favourite comics.
There are definite mechanical issues. As was suggested, the SEACAT system should probably be discarded for a more tested/familiar system (although, it might be a bitch to rip it's sticky tendrils out of the elegant and eminently gameable Caravan system). A further product fleshing out this system is hinted at. I don't know if I'd be overly interested in further mechanics, but more details on the weird races and classes that inhabit this environment as well as some more concrete descriptions (and lush illustrations) of the 'monsters' would definitely be welcome.
The Caravan rules provide a fun sub-game for the players to engage in, hopefully distracting them from the lack of combat/detailed side-quests.
Side-quests/dungeon-like structures are hand-waved (the product would have been utterly unfinishable/unpublishable otherwise) but more than that, it seems almost intentionally abstracted. Like the players find a location, say a mysterious pyramid in the wastes, they roll some dice, they lose x days, extract y trade goods and lose z life. Maybe throw in a key encounter with a boss NPC/monster that inhabits the place and let that modify the results. No dungeon map, no searching for traps, no delving. The crawl is the road, the discoveries you make along the way to be run more like rooms than whole installations unto themselves. The option is always there, but then it's up to the 'CAT' to design and run something. The average UVG character is too foofy for tactical dungeon clearing, so that's another argument for bringing in your own favored ruleset if you and your players want to put a little more time into the roadside distractions.
As I mentioned before, the language is often florid, opaque and a bit texturbatory, but never overlong or superfluous. It definitely sets the mood especially when combined with the art (which with a little reading almost always corresponds clearly with something on the spread (which is a BIG DEAL)).
This is above all a fantastic read and for sure a book to enjoy pride-of-place on the bookshelf or coffee table. It definitely can't be run straight out of the box and will drive BtB people fucking crazy with it's story-gamey 'yes-and' and 'do what feels right in the moment' hand waving instructions. I could see this working with a group of friends who maybe havn't played in a while or with casuals who want to geek-out without immersing themselves in rules arcana. Some beers, some weed, some caravan rules for that one barrister/attorney-at-table and you're looking at a solid night at the cottage/day in the basement that people will be talking about for a long time to come.
Highly recommended: 3 mushroom caps and 2 stems out of five? it was five dude, right? shit I lost count.