Just got my copy Friday of this book, and I have to say, it exceeded my expectations greatly!
The combination of artists this time was fabulous, it's not the all one theme type I saw in some earlier boxed PS sets (although I am a DiTizzleri fan, I love colorful, thick artwork too). They went into much better detail on the places to go/things to do in the Abyss than I thought they would. I mean come on, who didn't want to know what stomping through the rotting mushroom fields of the Fungus Queen's demense would REALLY be like? And if you didn't, well if you game with our DM, you're enjoying the ride anyway...
Really neat was the info/dice roll panels at the end of some chapters which tell the DM what knowledge your characters might have heard or learned regarding specific monsters and demon lords. Our group has been playing since we were all about 10, so 20 years or so, but the Codex is very user friendly I thought for developing some good campaigns. Of course they spent the majority of time on the biggies...Graz'zt, Lolth, Demogorgon and some others but I was glad to see some new characters and lieutenants peppered throughout as well. A VERY good section on possession and the effects on PC's as well as the motivation of the tanar'i in a way easy to understand for players.
If the second one is as good as this one, this will become my favorite set of D&D books of all time, excepting Hellbound of course and the original PS boxed system.
Speaking of the second one , I am hoping we will see in Tyrants of the Hells:
The same good artwork, detailing the fortresses and levels of Ba'ator and the personalities there.
More details on the Reckoning, who fell out of favor and the possibility of using those malcontents as NPC's in a Ba'atorian/PS campaign.
The physical descriptions and personalities of each of the Dark Eight, as Colin mentions in Hellbound each of them are usually encountered in human forms and almost never as pit fiends due to the nature of their duties. I imagine this is especially so with Furcas, Zimimar and Zapan since they deal with the "front parlour" more than the rest.
Would like to see some additional spells brought out. The Abyssal version had some wonderful (or terrible, depending on your viewpoint) spells which apply to characters who become enthralled, servants, etc. I am thinking many of these would apply equally well to the Ba'atorian disciples but just inversing them would be lame, there should be some new ones too.
Some information on the Ba'atorian Embassy in Sigil and it's history.
And of course, political intrigue is a must. It's what gets our PC's into so much trouble.
Well, that's my two cents. I do have to say, this book was definitely worth the $30 I paid!
Yeah, it was very good, and I was a little shocked at how much Planescape was in it, besides all the revisited Planescape Abyssal material, there's even a section that deals with various factions (Doomguard, Dustmen, Xaositects, Sensates, even the Planewalker's Guild) and how they relate to the Abyss, and a number of mentions of the Fraternity of Order and Sigil, and a Dustman fortress in Thanatos.
The Lost Annals covers even more.