(Let me just say that this review is based off of Seasons 1-7; I haven't gotten around to watching the episodes after Michael left).
PLOT: Well, basically, the title. Adults working in an office for a paper company, under their boss, Michael Scott.
CHARACTRS: MICHAEL. Certainly the best character, in my opinion, bringing in almost all of the humor of "the Office". There's also Dwight, a geeky paranoid kiss-up, constantly trying to get rid of Jim, the office clown. The interactions between Dwight and Jim are usually pretty funny as well. Pam, introduced into the show as a receptionist (moving on eventually to being a salesman) is Jim's love interest. There are a lot of other unique characters working at the office, such as Angela (the uptight Christian) or Creed (an old con-man). This show provides very great character-driven humor.
ROMANCE: Mainly between Pam and Jim. They end up getting married and having a child together. There's also Erin and Andy (a little on the dull side, though) and Michael and Holly, which ends their story arc on a positive note.
One of my favorite things about "The Office" is that nothing ever stays the same. Like, there's a lot happening between seasons 4 and 5. And that's really cool to watch, because it isn't predictable.
Overall, this show is a comedy legend and it continues to impress me to this day.