I LOVED the first season, but, to date, I haven't watched any of the second or third season. Not fully sure why, I guess it's mainly cause I've heard from way too many sources that show now sucks so bad that I guess I just don't want to ruin the memories I have of the first year...
Be warned the second and third seasons get pretty terrible. It seems to be turning around now though.
Yeah - series 2 is not as good as 1, but worth a watch. If you're expecting it to be really bad, you might find yourself surprised; I find that I am always disappointed with stuff that gets loads of praise, but enjoy the stuff that gets slated more than I expect to.
I liked Season 1 except the final episode. All that build-up to what I thought was an anti-climactic season finale. I lost interest after that and the few times I've checked it out after didn't raise my opinion any. It seemed like they had "Lost" isease, where they alluded to having a Grand Design but then really didn't.