Season 1 was brilliant as a new idea that was brought to television. Noone saw Nina being a baddy and it was executed wonderfully, especially with it not ending on a positive note as everyone expected.
Against the other series, sure, it's not as great, but for people who are watching 24 for the first time it's really good. In the future series everyone just knows Jack Bauer and knows he's the goody and knows he's a superhuman. In the first one he was a new hero and could be ****ed with. Now he's just too hard and you know he'll never die or anything