To her, ghosts appear to be normal people walking around as if they are living (well, if it wasn't for the walking through objects and being able to make things fly around stuff). If a person dies, and they aren't quite ready to go, their spirits stay in the living world haunting their loved (or not-so-loved) ones.
This season does a really good job of setting up the universe and rules of the series. These ground-rules include the fact that ghosts sap their energy from the people around them and how spirits that died unexpectedly are often confused and violent until they start interacting with the living.
Ghost Whisperer: The Complete First Season, in particular, is mostly comprised of "bringing families together" episodes. These tend to follow very predictable patterns that, while a bit contrived at times, are all for developing the characters of Melinda, her paramedic of a husband Jim and Melinda's co-worker, Andrea, as well as all of those characters' families.
For the most part, you can watch these episodes in any order. There isn't a lot of reliance on previous shows, at least until you get to the last three or so. There are a few appearances of strange figures that foreshadow the events of the season finale, but as long as you see all of the episodes before the final three or four, you are pretty good to go.
As for the season finale itself, I have to say, it has one of the biggest twists I have ever seen in a TV series and while I suspected something like it to happen, it still caught me completely off guard and was really effective. Unfortunately, I can't go into any details without revealing the twist to readers who haven't followed the show, but it is really good.
This boxed set contains a good number of special features including deleted scenes, bloopers, various commentaries and featurettes that all do a good job of filling out the last disc.
Ghost Whisperer is a pretty good series and while the first season isn't the best, it lays down the framework for the much better seasons that follow. This show isn't for everyone, but fans of more real-world grounded sci-fi shows (like Heroes or The 4400 will like this series.
