First, the good things about Nehrim. I personally thought that the true beauty in Nehrim was in the dungeons and in the detail. This was by far the amazing part of Nehrim. Everyone probably has their favorite dungeons, but I most fondly remember the dungeon that led into the dwarven city. The beginner dungeon, the magically-infected mine, and the dungeon that took you through the spider-worms digestive track. The detail in Nehrim was also amazing, and was something that was much improved over Oblivion. I still remember the time when I stumbled across a ruined gypsy wagon and the time I came across the currently unused jousting/racing arena. My thoughts? Wow...
The story was interesting and engaging (though not quite on par with winning as the dungeons/world detail), drawing you in to suspect everyone and really ponder the consequence of your actions. The ending of Nehrim seemed a little anti-climatic, though, and wasn't as satisfying as I had hoped. And I wasn't drawn into the whole destiny versus choice theme that ran throughout the plot. While some people still enjoy musing over the destiny/free will ideas, I had essentially a long time ago came to the realization that the ideas of destiny versus free will were completely meaningless, since the outcome in the end is the same. The only character I became attached to was Kim (and maybe the old Abbot from the monastery), possibly because I was suspicious of pretty much everyone else.
Spoiler
And although I liked Kim's end (I felt she was wrong, and I might agree that she was a coward, but still liked her anyway) her death seemed redundant and unnecessary. I was also disappointed with the conversation options, but more on that below.
Okay, now for the bad. Nehrim, in my opinion, while exceeding in the above, fell behind vanilla Oblivion in creating an immersive and open world. While you could go a lot of places, Nehrim gave off the effect of "pathing" or "tunneling" the player through the landscape. You couldn't often venture far from the path, and hence large parts of the world were inaccessible. The fact that Southrealm was inaccessible from the beginning also bugged me. Truly open worlds don't do this sort thing. Two Worlds Two also adopted a system of new areas as you progressed through the main quest, though unfortunately to a much greater extent. As such, different parts of the world felt more like "levels" than part of a cohesive whole, and I had little desire to return to places that I had been following the Main Quest.
The other major stumbling block of Nehrim was instilling life into the world. Despite the incredible detail, cities, towns, and the countryside all felt lifeless. NPCs rarely had any sort of character or life to them, as they rarely had any sort of schedule or, even more infrequently, had any sort of dialogue option (disregarding quest characters of importance). Even then, quest characters only really had dialogue pertaining to the main quest, when I kind of wished that I could speak to them under less than formal circumstances. Oblivion's quest characters always had options where you could needle them with questions about the quest, and sometimes even discuss gossip. As a whole, Nehrim's world seemed an appendage of the main quest, and not a living, breathing world that stood on its own. Once I finished the main quest, I felt no desire to continue exploring.
All that being said, I give Nehrim an A+++ as an oblivion mod and a B as a game in general. As an open world rpg, which I don't really think that it fully is, I would give it a C-.
ALSO, I HAVE A QUESTION:
Nehrim is supposed to have an alternate ending, right? Upon finishing the game, I looked around for it because I wanted greater closure on the Main Quest, which felt rather unsatisfactory, but I can't evidence of it anywhere, other than the claims that Nehrim had one. I couldn't find any discussion of it whatsoever, or even a youtube video depicting it. Does it exist? What happens?
And now...back to Oblivion.