The series started off OKAY. The plot was written pretty solidly and each episode was predictable. It was written in the style that Medium was. Echo wakes up and takes on a new personality which was pretty interesting.
For the cons: The bad guys always changed. They changed too much. First the Dollhouse was the bad guy and the FBI agent was working to uncover it. Then it flipped, the show dropped that the Dollhouse was bad, totally ignored that part and then the bad guys became another Dollhouse. There was always an enemy and I found that the characters would hate one another at one point but then that hate would be dropped and they would magically become friends again. The series was clearly not written well. The writers obviously did not think the plot through. It started off as being written like Medium (well organized and well written) but then they flipped back and forth with this weird Apocalypse thing, bad clients, Echo becoming her own person, Catherine not mattering anymore, and the nutty corporation that was set out to ruin the world. Also some characters would agree with the enemy and the plot would get confusing because they weren't supposed to agree with the enemy.
It could have been a fantastic series but it flopped by the end of the first season.