It was brilliant from seasons 1 to 3, because it had the increasingly dark tone, and was a nice alternative to "Buffy." But ever since Paige came into it and Brad Kern took over the show, it deteriorated. I still love it and watched til the end, but seasons 6-8 were so hit and miss, it's embarassing, really. And what's strange is that I love Rose McGowan, and am not all that keen on Shannen Doherty, yet I know the Prue seasons were the best.
The continuity was pretty awful in the final years, I remember. Though there was some fantastic CGI in certain episodes, considering it was a TV show and not a big budget movie.