One significant improvement between the Guild Wars campaigns was the voice acting.
I haven’t heard much of Prophecies yet, but what I have suggests a need for better direction. It was as if they gave the voice actors individual lines to read without telling them what is going on, their motivation, etc. Maybe it improves; I am hitting Prophecies last. Factions was painful, and the subtitles were necessary. The voices themselves were not great, the voice acting and direction were random (not even following the emphasis listed in the subtitles), and then they added effects to the spirits’ voices to make them half-incomprehensible. Maybe there are some tropes of Asian cinema that they are faithfully reproducing, but after starting with how my character sounded in Nightfall, Factions just hurt every time … anyone came on screen.
But Nightfall is good, rather good. I enjoy both the voices and the acting. They are well-fitted to their parts, and not just because General Morgahn comes off as Morgan Freeman. Contrast the effects on the demons in Nightfall with the spirit envoys in Factions to show how to have the effect enhance the voice, not destroy it. Then we get to Eye of the North, and we have a range of good characters (not just Vekk). The quality of the lines in Nightfall was probably higher, but you must love Ogden (voice and lines) during the Norn arc. One simple bit I really liked was Jora, “Blood washes blood.” She says it three times in a short cutscene, but it has a different intonation each time. With the last one, she manages to imply hope, fatalism, and a suggestion that the wisdom of a thousand generations lies behind a three-word phrase.
Also, don’t you just love that scene between General Bayel and The Hunger in Nightfall?
It is much easier to find voice actor lists for shows than games.