Copy-pasting my lengthy comment from Quaddicted:

All maps here are huge (at least in terms of scenery, though often in playable area as well), but there's a mix of very "sandboxy" levels and levels with a more conventional structure. The sandbox maps include a desert town (fifth level), some kind of post-apocalyptic Paris complete with Eiffel Tower and huge demonic corpses bursting out of the pavement(7), and a abandoned Roman coliseum and surrounding complex (8). These maps all have open layouts with multiple widely-spaced key items to track down. I think these are the most successful because their gameplay matches the maps' size and scale: there's a lot of ground to cover, a sense of open-ended exploration that's more familiar from other games than from Quake and which makes you feel small, but also you're surrounded by MORE space that's not accessible but makes you feel smaller still. I think this is why these maps work so well. The other levels feel more like large-scale versions of "normal" Quake levels that stand apart from each other in their distinctive themes and gimmicks. I've commented before on my love for Blasocuyst (2nd level) with it's huge puzzle room, as well as the fourth level's dizzying and surreal take on the wizard theme.

With maps this huge there's always a risk of having too much 'empty' space, and I feel most of the maps here fared pretty well. I would maybe cite the first level (the island resort) and the sixth (the snowy mountain/village) as possible exceptions. They are both pretty wide-open once you get past the initial location, but have large areas that are essentially skippable and kind of repetitive, not particularly interesting in gameplay terms.

Thematically, the maps are a weird mixture of realism and abstraction. There's nothing linking the maps thematically except how out of place in Quake's universe they are. I mean, "realism" is not alien to Quake, neither is unusually otherworldly approaches to standard Quake themes, but it's strange (in a good way, I think) to see them in a single release, sometimes even combined in one map (the wizard level looms over scenery that is essentially a collage of photos of war-torn cities; the huge corpses in otherwise realistic Paris). Taken as a whole it creates a kind of uncanny effect. I'm reminded vaguely of the Doom WADs produced by a Russian team called Clan B0S, which also combine realism and abstraction in their layouts and aesthetics, to different (but still uncanny) effects. They also, incidentally, have drawn a similar mixture of praise and condemnation from players...

Gameplay-wise the maps are generally pretty tough on skill 2. Maybe a bit excessive at times in its use of Drake entities but it's not the worst thing to be guilty of.

It's worth noting all these levels can be played from shotgun start. Cool feature, as the maps are time-consuming enough, so it's good to be able to just skip to my favorites and replay them as I wish.

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Addendum:

I should add that performance-wise, these are demanding maps, so how it goes will depend on your rig. For my part, I nearly found the final map unplayable, but only at the beginning: the combination of a low framerates and being attacked on all sides meant I had to restart the level several times and almost gave up in frustration, but once I cleared out the initial area and went into explore mode I got really into it.

In any case, this is a unique mapset, not one to appeal to everyone but at its best it's some of the most memorable Quake content out there. 

Newbie to Quake mapping here. I was looking at Drake's documentation a while ago, and it said nothing about these guys being in there. I bring this up because I was able to get on one of the railings and found Armagon just hanging out. Is there a complete documentation somewhere? 

Sadly the official documentation doesn't list all of Drake's monsters, items, and features. If you look in the qc folder of the devkit you can find entries for these undocumented findings. Or just hit me up on Discord Hydl (Orl)#3312 and I can provide you a FGD of it. 

Glad to see this. I gotta say though that the lightning effect in shib7 contributed a lot to the atmosphere and I think that it's even worth the performance hit of using one of the engines that supports it, especially for a first play through. I've been holding off on shib8 because I'm reluctant to close the book on Ter Shib but that screenshot is really amazing.