There were lots of things going for that plot. The dialog is not bad, some of the jokes are even quite good (Paige still has problems with her orbing powers), the situation offers a very interesting parallel with Leo's, and it's nice to see other Whitelighters for a change (especially since those two are annoying, so you don't really feel sorry when they're attacked).
But there are several huge problems with the whole episode, mainly a) that interesting parallel ? nobody ever mentions it, b) the sisters don't look the least embarrassed at having mauled or potentially killed people, they even joke about it, and c) the only explanation we'll ever get concerning their transformation is "oh, it is a rare phenomenon, so it is bound to be terribly bad... but since it doesn't last, we'll talk about it next time". I was left blinking at that one, since that is totally NOT the sister's usual philosophy. And to crown it all, those beasts are the worst FX ever.
But there are several huge problems with the whole episode, mainly a) that interesting parallel ? nobody ever mentions it, b) the sisters don't look the least embarrassed at having mauled or potentially killed people, they even joke about it, and c) the only explanation we'll ever get concerning their transformation is "oh, it is a rare phenomenon, so it is bound to be terribly bad... but since it doesn't last, we'll talk about it next time". I was left blinking at that one, since that is totally NOT the sister's usual philosophy. And to crown it all, those beasts are the worst FX ever.