Well, that’s up for debate. A lot of people, me included, felt that she was more window dressing and basically had one “look” upon which she relied far too heavily; which is best described as “pensive pouting”.
She didn’t have much range as an actress. I think she was basically successful because of her looks.
But the plot and storyline is what I found fascinating as well as some of the auxiliary characters from the courier agency.
And the set decoration was spot on also. Jensen Ackles didn’t appear until the second season but I think his acting range did a much better job of portraying what these transgenic kids were going through.
And they also had a couple of convincing baddies hunting them: John Savage and Nana Visitor (DS-9) both veteran character actors.
Weatherly was also good but oh so serious, which the role mandated (unlike the more
nuanced part he now plays withthat dash of rakish humor as a break from the serious.)
But, Alba was at least tolerable and didn’t totally screw up what was a really fascinating storyline and unique little fiction world created by Cameron and his team.