Charmed is not known for its season openers. It basically has two distinguished ones- the series' opener, and the series' changer- Charmed Again. Considering that, this is probably above average when compared to the other 5 openers.
The story itself is pretty good. The demons involved, Guardians, are nothing special and are easily disposed of. Piper is a confusing mess throughout the episode. She coldly rebuffs Leo's famous attempt to propose to her, and it seemed to me that the writers really struggled to give Piper a comprehensible reason as to why. Ultimately, we know it was just to drag it out, though they managed to do that only until the end of the episode. Season 3 wasted no time getting Cole Turner in the mix, and Julian McMahon is good from the get go and great in the scenes with Alyssa. We went all Season 2 without a long term antagonist, and not only has that been addressed, but in Cole we have something new- a long term bad and love interest simultaneously. It was a great scene when Cole vanquished the judge, and I do believe that Cole is the first demon to shimmer on the show, which is definitely the coolest way to travel. It was also a well-done transition from the end of Season 2 to give Phoebe the power to levitate. We don't see it much here, and unfortunately, we don't see it at all after Season 6, but it was still a great idea to add something new to the series in the first episode of the season.
The big courtroom fight was clearly the main action set of the show, and though it was well-choreographed, I thought the whole scene was ridiculous. Prue could have take care of all those guys with her power and never needed to go hand-to-hand. When since did Prue and Piper become martial artists? Whatever. It was all about girl power, I guess. And, of course, at the end Piper sees the error of her ways and agrees with Leo, which is always a good idea. I would like to go through the entire series once and count the number of times the sisters foolishly refuse to listen to Leo only to have it bite them on the butt.