Pros:

• Great addition to one of my favorite maps!
• I like that you added your own features to the map while keeping existing areas and keeping the theme of the map.
• The lighting is consistent through out the map.

Cons:

• The added sections do not seem as detailed as the rest of the map.
• The additions seem too wide open, there are just long passages with few corners or ladders or something.
• The new sections are mostly hidden behind doors, making them not that obvious.
• These new paths are not required to get to the objective.
• Loss of 3D skybox. D:

Improvements:

• Improve some of the displacements so that they are more extreme as well as adding details like more props or overlays or something.
• Add some more obstacles or something to support short-ranged combat.
• Open some of the sections up or show that the doors can be opened, as all of them are not and you are forced to walk into a static door without noticing.
• Block off some of the preexisting passages to make players go through the new paths as the player could just play on the existing layout and win and not explore the entire map.
• Add a 3D skybox again! It's not that big of a deal but improves the visuals of the outdoor section.

Notes:

• I really loved the additions you added, don't mind that there are more Cons than Pros, but I kind of generalized the good things and knit-picked at parts I thought needed improvement.
• I think the additions would improve gameplay but are not necessarily needed.

Rating:

• For the above reasons, I rated this map a 8.89/10. Good work. (I rated things like detail and ambience lower because of the lack of detail and 3D skybox.)