This is a strong second installment to the opener of Season 4.
Here Piper and Phoebe practically do a role reversal with Phoebe now being the uncertain and grieving sister and Piper starting to insert herself as the new leader of the Charmed Ones. Piper is still too rough with Paige though, and Phoebe continues to be the better communicator with their youngest sister. Rose McGowan, as Paige, continues to impress, and her scene in the church when she discovers her power to orb objects is classic. The fact that she also flees the sisters and goes running to a BF when in trouble will remain an unfortunate character-trait of hers throughout the series. Should the Source of all evil just be able to blithely walk into a church? I would think not. So, though demons do so throughout the series, I was glad that at least the Source was not able to in this episode, as the gargoyle protectors of the church stopped him from entering. The part where Cole was nearly killed was somewhat nonsense, and again, the threat of exposure was completely unnecessary considering the end of Season 3, besides being preposterous. But at least it all ended well.
Paige's near turn to evil was very well done, as was the final battle between the Source and the sisters. Why the Source would just leave the sisters alone rather than trying to vanquish them right there is somewhat a mystery, but I guess he didn't feel he had the power yet to take on the Power of Three. The ending at P3s and then back at the manor was fantastic, as the sisters appear to finally let Paige in. Very touching scene.
I will complain briefly here that it is unfortunate the writers of Charmed decided to go away from the Lucifer-like representation of the Source in All Hell Breaks Loose. That was by far his coolest appearance. In this season, the Source becomes like just another powerful demon, and in this episode, he is even doing his own dirty work. That is too bad, IMO. Would the Lord of the Underworld really be bothering to possess humans? Don't see it. I think the writers could have left him the way that he was.
Otherwise, great start to Season 4. Rose McGowan is just adorable, and I love Paige's powers. Since Piper is the heart of the series anyway, it is great to see her take the leadership role. And this is also a brief great time for the series when Cole, Leo and Phoebe all have their powers and are working together. Great things are yet ahead.
This was Charmed's first attempt at a two part episode to start a season, and it would forever be Charmed best attempt. Really, the more I watch these first two episodes the more I appreciate the writing of both. With Prue's death, they needed to get this season off to a strong start, and they did that. Fantastic job.