I only have two real complaints with the game: the lack of a unified, easy to access word map (full world) and the lack of challenge, especially in the latter half. I didn't mind the ease so much, because the combat is so consistently fun, but now that I've completed the main quest I'm lopping through bandits by the dozen, barely taking a scratch. There's plenty to do - keys, demon doors, gargoyles, job quest lines (the assassinations are a hoot), etc. - but none of it especially difficult.
I really miss a good world map. In Oblivion it helped me identify where I was in the big picture, and make sense of the various locations and how they interconnected. In this game, even though it's broken into regions, I wish I could easily see how the pieces fit together better. Albion is artistically consistent, but the game world is literally fragmented, so I needed a way to pull it back together. Going with bread crumbs over a world map was a big mistake, IMO.
Some other minor quibbles, but really the game is wonderful. The combat systems are superb, there's TONS of fun side quests, the main quest is long and enjoyable, the writing and dialog were consistently excellent, the music and audio design are stellar across the board. Good number of fun dungeons (a major shortcoming of the first game) and there the subsystems of character interaction, town economy and relationships feel organically fit into the whole. The more I pay attention to the details of the game, the more I find.
Wonderful stuff.