He was pissed at the ending. I can guess by his comments he did really enjoy the game and when it came to tne ending felt very let down and posted that. I think it's ok to post negative comments and dislikes but it was very rude and could have been worded, well, shall we say much more constructivley?
One other game that had a really crap ending was Drakan, that started a whole flame war (no pun intended!) on several forums as gamers vented their anger. The devlopers explained that the crap ending was due to being rushed to meet the deadline and had already planned / got funds for a sequel. I think Larian originally planned for the Flames of Vengeance add on to be part of the original game but didn't have time to fit it in.