I got right near the end of season 1 but i stopped there. It was good but cant say that it really gripped me to be honest. Was the same with the shield that was really hyped, i got near the end of season 1 and then found myself watching other things.
I loved the first couple series of 24 and then maybe one other when jack came back 'from the dead' so to speak but the ones inbetween those were pretty boring too.
For me, these cop/political series should stop after a couple of seasons. Though does sound like a lot of you enjoyed more than a couple of this so i could be wrong =]