When Charmed first started off, it felt more like a Buffy knock-off and held only mild interest for me. But the series eventually came into its own and by the time this season came out, it had established a rich mythos and universe. As one would expect by such a long running series, jumping into the final season will leave a viewer feeling a bit lost, so of course, you wouldn't want to see this season until the first seven have been watched.
Charmed: The Final Season starts off with the funeral of Piper, Paige and Phoebe (yes, the Charmed Ones). At the end of Season Seven, the trio (and Leo, Piper's husband), fake their deaths and assume new identities in order to "retire" from the demon-hunting business. For the most part, their disguise works and everyone (including the elders) leaves them alone, well sort of.
While trying to adjust to a "normal life," Paige is given a new charge and must look over a young witch who is taking demon-hunting into her own hands. The group decides to use this new fighter, Billie, to help relieve some of their supernatural stress, but it isn't long before their faked-deaths are revealed and the Charmed Ones have to go back to their old life.
This season has quite a few good episodes that all lead up to the big series finale. Along the way, Leo will be sought after by The Angel of Death, Billie will look for the demon that took her sister and then there is the final battle with a new and ancient evil. Another story arc is Phoebe's short-lived marriage that is induced by some stray magic and the consequences that follow, as well as Paige's attempt at a personal life and how her new boyfriend will handle her secret life.
Along with the standard TV series features (commentary on some episodes, a couple of featurettes and some interviews), this DVD set does a pretty good job of wrapping up the series and should definitely be picked up by any existing Charmed fans.