The level and world design is truly superb. When I think of other open-world rpgs, even rpgs as a whole, I can't recall many levels that are as fun to explore as the dungeons you find in Nehrim. Some of them are just that good. The soundtrack is great as well.
Story is cool but written awkwardly. This might be a fault of the English translation, but it generally felt that many story moments didn't make the intended impact. Compared to its sequel Enderal, the characters are not as compelling. However, the story as a whole is elevated by having interesting themes and a willingness to have fun with its setting.
Worst part of this is the constant crashing. Having played both versions, I believe this instability is more pronounced in the steam version.