While I certainly had fun with KotB, it's not without its... hiccups.
It really, REALLY could use some editing. Stat blocks are jumbled in willy nilly with flavour text, stuff that the DM can share with the players, like room descriptions, are jammed in next to stuff that should be secret (leading to the oh so fun, "Oh crap, I shouldn't have read that" moments)
And, basically, it took every single monster in the Basic rule book and jammed it into one module. It lacks structure and theme. You've got a tower of orcs basically.
IMO, the map is too linear as well. Sure, you've got a bunch of choices between entry points, but, once you enter a given cave, it's a pretty much straight line to the big boss at the back of the cave. Yes, there are some branches, but, each branch generally only leads to a single room. For example, Cave A. You enter into a T junction. Go left and it's one room, go right and you do reach another T junction. Go straight and it's one room, turn left and you come to another T junction - left gives you one room, right gives you one room.
Note, not all caves are like this. B and C are linked by a single secret door, so there are some possibilities. But, by and large, each cave is a smallish linear dungeon crawl.
That being said, I don't think this is a bad module. My biggest single complaint is that it isn't a very good module for what it's purpose was, or at least what I understood it's purpose to be - and that's teaching new DM's how to design an adventure. There are a lot of bad lessons contained in here - lack of organization, lack of detail, and just too damn many different monsters jammed cheek to jowl in one area.
I think that The Lost City should have been the module included in the Basic set. To me, that's a much better module for teaching fledgeling (and decidedly young - Basic was intended for 10 year olds) DM's how to design a good adventure. You have a multicursal map (including a VERY cool spinning tunnel for accessing different points in one of the levels), a strong theme and a fantastic set up for stories - three detailed rival factions vying for control while a 4th secret faction works from the shadows.
Granted, that might have been a bit difficult as B4 came out in 82, not 79, but, hey, I can dream.
