When I first played Dungeon Siege as a kid, I accidentally played through the entire Legends of Aranna expansion pack before playing the original Kingdom of Ehb storyline. Because of that wee mistake, LOA holds far more nostalgia for me than the main campaign. lol
I've heard that there are issues surrounding this expansion pack's ownership/copyright(?), but that's honestly what makes Legends of Aranna a great pick for GOG's preservation project. It would be such a shame for all this additional content to remain in legal purgatory forever. All I know for sure is that I'd paid good money for LOA, were it available here on GOG.