Overall, I think it is a good continuation of the Gothic story. It was good to see again the old faces. This game however is fundamentally different then it's predecessors, so you have to set your expectations right. The story is rather interesting, but very linear. It does not have the same feeling of exploration as the previous ones, rather, feels like a dungeon crawl, where you clear an area, and move on to the next.
There is one great downside of the game though, and that's stability. I've played it on Windows 8, and after fiddling with the compatibility, and setting the sound quality on the system to 24 bit 48k sampling (both are recommended and helps a bit), it was mostly playable, but still frequently crashed. I recommend saving often.
I still think it's a decent game, worth trying if you liked the previous ones, but does not have much replay value.