For your first map since Reach this is pretty decent. However the proportions and basic forms are way off the original shown in the movies. The outer wall is not circular enough plus the whole fortress should have been set higher.
How many pieces did you put onto this map? I'm wondering, because I had around 500 pieces in Halo 4, but came to a more accurate replication.
Maybe you could try to be more efficient with the objects you're using? I'm surprised that the object count hindered you to make the secret staircase. Lighting issues shouldn't be an excuse since you can set the "Light Bake" to OFF for pieces that are in the light anyways for example and therefore lower the lightmap.

 

Shadow, forget what this guy above says, this map is a fantastic rendition of Helm's Deep. I have dozens of files and photos for this particular fort and having made 3 versions of it on past Halos, this is super freaking accurate. I only wish you had budget to do the inside of the castle, the walkway on the left side of the mountain, and the hidden exit on the right. Rock on dude. Freaking awesome!

 

I can prove my points with pictures, Cujo, if you need help remembering the exact look of Helm's Deep. I find it pretty amusing that you have got "dozens of files and photos" for it, but can't see many differences between this version and the one from the movies.
Also, desregarding my points with no real counterpoints is not that respectful I would say. If someone like me, who is absolutely dedicated to Tolkien's world, gets ran down like that it doesn't feel good.
However I will cave in, since your digital p**** seems to be way bigger than mine.

 

1v1, first to 84 kills on it. I call Legolas

 

Whoa buddy, all I said was forget the guy above. I was completely positive towards OP's post. You however, mister digital p***** man, likes to think your sh*t smells better because you're a 'bigger' fan. His map is fantastic. Get over yourself Saruman.

 

I'm so sorry for setting the highest standard when it comes to LOTR. Once again, it's a decent recreation, but far away from being fantastic; I don't understand why you try to "defend" his map even though there is no defending needed, since I am always honest and only raise my word about a subject where I'm experienced and learned.
So please end your ridiculous argumentation here or else I have to post pictures... That would even more cast a slur at you.