Warning: There will be minor spoilers as a fairly important game mechanic is added partway into the game.
Let me start off by saying that my experiences with the original campaign weren't entirely pleasant. The plot took forever to get anywhere, I didn't like any of the party members, and the bugs, oh god the bugs! It was a little over a year ago that I played through the OC, and even that long after release there was one spot where I had to go online and look up how to go into the command console and trigger an event that wasn't working (and thus wouldn't let me advance the story). Maybe this has been fixed since then, maybe it hasn't. God knows after installing MoB and Storm of Zehir, the game spent somewhere around an hour and a half downloading and installing patches, so maybe that part was fixed. I mention this for two reasons though.