Particularly, I'd like to know about the following aspects of any such mod you may have played:
1. Lore-friendliness - Is the mod lore-friendly, to TES lore? I consider the incorporation of some locations from other works to be somewhat lore-unfriendly, but not terribly so. However, if it makes major references to well-known characters or other non-TES lore such as races and items/artifacts, that goes well into the lore-unfriendly realm in my eyes.
2. Completeness - Is the mod finished, functional, and does it contain respawning enemies throughout its' tunnel systems?
3. Size - I'd prefer an impressively large tunnel system worthy of the name "Underdark". How does the mod you've played stack up?
4. Overall Quality - Was the mod good? Did you enjoy playing it or consider it a "keeper" for your game?
Thanks, any responses are highly appreciated!