Regarding the blind spot/s, I can easily redesign the layout in order to minimize or remove them.
When i initially designed the dungeon i had CQB tactics in mind (I'm an infantry veteran)
Never let a layperson talk you out of including an element in which you have expertise (although comments on presentation are valid, since laypeople have to understand it. An area that isn't covered is tactically interesting, as is figuring out how to take advantage of the blind spot when there is no obvious way of retaliating against the attackers from it. And there are all kinds of reasons why the resources may not have been expended to completely cover the area, as you are no doubt aware.
The description thereof is another matter, and I would have been inclined to shade the area on the map that is covered by each arrow loop, as well as the area of overlap, and state in the text that characters in those areas are vulnerable to attack from the monsters. This would also likely identify other, smaller blind spots without having to engage in lengthy descriptions. I'm betting there is one in the northwest corner, which makes the door more attractive, but requires you to pass through an area of crossfire. It also obviates the need for a description of the monster's tactics, since it should now be obvious to even to those who are not tactically inclined.
I agree that the descriptions could be shorter and have more flavour; the descriptions build a mental picture for the DM that allows him to improvise. In my view, too much detail defeats itself because it can't be found when needed, or in an impediment to understanding, because of navigating a larger amount of text. Also, I find that flavourful language can make your intent clearer. A good example is the hinges. If a DM described hinges as "rusty", I would not assume from that that they has lost structural integrity. But if the door was described at "hanging loosely of dilapidated hinges" I might be inclined to try to do something with that.
The position of the shield is important and should be highlighted on the map (I had to search for it.) I think you should mention the weight of the barrels, since there are various tactical reasons you might want to move them, and the DM needs to know how hard that it going to be. Also indicate how much space they take up, since you may have the whole party trying to cram into that corner. Both of these details will otherwise experience significant table variation, since estimating the size or weight of a "barrel" is beyond most DM's experience.
When I first read this I fixated on the sulfurous smell in room 1. I don't know if it if telegraphing something later in the dungeon, or if it is just random dressing. I am not a fan of random dressing without a purpose, it invites lengthy and pointless investigations that require the DM to improvise a bunch of irrelevant material, and players don't usually need help getting distracted (they are perfectly capable of manufacturing their own red herrings). If it is telegraphing something later in the dungeon, depending on what it is you might want to repeat it in room 2 (unless its absence is significant).
I think the carving needs more attention. It is an opportunity to provide hooks, or foreshadow elements later in the dungeon. The ruby latch is also incongruous if the initial description does not include features for the party to investigate. Also, it is not clear enough that it is a ruby shaped
button (what is "ruby
shaped"?), as opposed to an actual ruby; I missed that on my first readthrough ("ruby" is bolded and underlined, "shaped" is not) and think it could cause confusion.
I agree that the source of light in room 1 should be called out.