I finished playing through your hold, it's rather good as hold overall and very good as one of first custom JtRH holds - nearly each puzzle took me some time. Only thing that is missing are scripts or just dialogs, to expand story. Roof looks amazing. Here is short review of each room.
Entering
Entrance: Just quick showdown with two members of my favourite new monster from JtRH
1E: Actually this room took much too much time. I tried to do this room in much harder way that it should be done (I tried to block wraithwing on goblin).
1N 1E: Very good room made from three sections. Killing serpent is easy, but I made it using just luck or intuition

. Second part is really good as I like trapdoor mazes - not too difficult but not too easy as well. Rattlesnake is good interval between two mazes. Third part learnt me that tunnels work slightly different than I thought

.
1N: First part easy - just survive attack of mud babies 'til bomb blows. Next fun playground with rock golems. Overall good, fun room.
2N: This is quite tricky. First some speed required, then much mud cuting and few good ideas. One of harder rooms of 1st level.
2N 1E: Good but rather easy room - brilliant example of usefulness of rock golems

.
2N 1W: This rattlesnake is much too easy IMHO.
3N: Roaches + Spiders - nothing special.
Main Halls:
1N: Wonderful puzzle - quite long, showing some of potential of guards, it somehow reassembles me last room (w/o Slayer) - all these roaches which keep coming until the end of room when you must be doing something rather different than slaughtering them

. Really good room. I think that you intended to have 3 roaches from each queen after hitting orb, but queens don't like to spawn on open door - is it bug?
1S: This room has much much more potential, it's fun but too easy and short.
1S 1E: I hate this room, maybe because I hate strange rules of wraithwing movement, especially when something limits your movement. It was frustrating to direct last wraithwing on such difficult floor.
1E: Quite long but also quite easy. I just had some problems in observing actions of both Beethro and his mimic

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1W: I had incredible problems with these eyes - usually they are easy for me, but here I spent much time trying to kill them wrong way.
2W: After my problems in 1S 1E I thought that I'll spend eternity in this room, but It was cleared very fast - on second, or third attempt. It was probably just easy after all

.
Ground floor again:
Entrance: Nothing special, but fun. I just needed to observe roaches and clock and to hunt for queens in proper order.
1S: Snakes nearly commit suicide without your help, but trapdoor maze is not so easy and very good (still easier than that on first level).
2S: Moderate room, some parts quite hard, other rather easy. Some sections are tricky (ie. wraithwing section and rock golems).
Castle roof:
Entrance: Nightmare - snakes on orthogonal squares. Easier than I thought but not easy. Room could be bigger, could have something behind green doors.
1W: Easy wubba puzzle, but fun to play and solve. I am not entirely sure that wubba is needed to succed in this room but I haven't found any method to survive without wubba.
1N 1W: Very good idea, Rather hard room, especially second part.
Good work.
1N 1E: Too easy, maybe use second rattlesnake?
1E: If entered good way room is easy, if entered bad way room is much harder.
The inner sanctum:
Entrance: Similar to first entrance of hold, funny form of timer, but I killed guards much before seeps could hurt me

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1N: The best room of entire hold (as final room should be). Long and quite hard, final showdown with Slayer. Similar to 1N on 2 level you must do "
thing"
killing armies of roaches, but here you also must avoid Slayer and his wisp. "
Thing"
is total destruction of mud and tar to drop black gate. It's quite hard to concentrate on destroying tar and mud when wisp or Slayer follows you and roaches have taste for your blood.