First season was pretty good. It was a bit convoluted toward the end and I'm not totally sold they knew where they were going with it. The second season was unbelievably bad. I didn't make it through the whole season before giving up. I won't ever bother going back; those I trust with opinions on media said it was pretty pitiful.
The third season was better, but still not as good as the first season; however, I don't much care for witches and the like. I found none of the characters appealing in any way.
Fourth season? Waiting on the SO to start it. She digs these more than I do, so we'll start and watch it together.