Played through siege of Dragonspear for the first time this week. Thoroughly enjoyed the expansion pack, I think that Beamdog did a really good job with it. Hopefully a few bg2 mods will address some of the loose ends that it creates though.
I absolutely loved how they introduced Irenicus, Caelar Argent was an interesting character, and the ending in Baldur's Gate was great. The large scale battles definitely had an epic feel to them and the maps and cinematics were gorgeous.
I really don't get why it was so harshly criticized.