It doesn't suck. Overall, I really liked the plot. It moves well, and tells an interesting story. And is definitely darker than the original.
I also liked the vast amount of new items and upgrades available. Cool stuff. The new robes are nice as well.
However...
It felt like there were quite a few sub-plots and such in the game that were never fleshed out. I'd guess that it was due to not enough development time, but it's kinda frustrating to have something lightly sketched out, and then never followed up on. Some of which seemed fairly plot-related as well, not simply side-quest type stuff.
Also, the frustrating lack of progression in conversations with the NPCs.
I'd still give it an 8/10. I did enjoy it, and have already started playing through again.