Arcania - Gothic IV.
I won a bet on the quality they managed to produce, but it was the final nail in JoWood's credibility. Horrendous barely scratches the surface of the horrific crimes committed against "RPG" history in this title - added to this, they managed to commit every single "console development crime" in some kind of machoistic stereotype fulfilling ode to inadequacy.
Yes, it was that bad. Invisible walls. "You never liked swimming". Revenge of the bland clones from TES II. Add to this the CEO proudly declaring that the game "was what they were aiming for". Which shows you why the industry is in trouble.
On the converse side, Risen provided a good 20 hours of joy before it ran out of steam, and allowed us to re-visit Gothic 1 - sadly, they failed to actually code any dynamic world behaviour in there, which was a hugely missed opportunity (*cough* If the player has denuded the entire game world of fauna by the end of chapter 1, you should program the game so it notices this and then ramps up the ecosystems *cough*)
[edit]
Sorry, I missed pointing out that Arcania managed to bring a whole new level of bugs to a console game which are (historically), not supposed to suffer from bugs (too much, ahem ahem). Practically the only thing they brought from the PC history of the title was huge great stonking clonkers of bugs. Not a proud moment for coders anywhere.