OK, I started watching the show for the first time three months back on DVD. The first two seasons were great and then in season 3 a drop began. I powered through season 4, almost ready to give it up and then season 5 happened and the show exploded again.
I love shows that know when they reached a low point and managed to reinvent themselves. I love how season five is as quirky, light-hearted and funny as season 1 without losing the seriousness of the main story. Go on Castle.