Something that I think is often lost on some of the newer Doctor Who fans (an incongruous term when describing a show about a time traveler) is that the show is supposed to be scary. Often, The adventures of everyone's favorite Time Lord get compared to what outsiders consider "sci-fi". When comparing the show to American counterparts, people tend to point to shows like sliders, Quantum Leap, and of course Star Trek. The thing is that none of these shows are actually in the same Genre.
While Doctor Who is admittedly SF, I have maintained for a very long time that the nearest American equivalent to the show is in fact, The Twilight Zone.
What I think is most often lost on outsiders is that Doctor Who, at it's core is a Horror show with elements of Sci-fi to string it together. It's supposed to be scary. Often, you will hear British celebrities on talk shows and such talking about how as children, they would watch the show from behind the couch. Craig Ferguson was particularly adamant about how much the Daleks scared the heck out of him as a child, and trying to explain to his American family why something that looks like an espresso maker would be a "Scary thing" was rather difficult. Americans, particularly fans of the original "old School" Who episodes were generally introduced to the show through PBS as teenagers or adults. By the time you're in your teens, the Daleks aren't really scary... just cool cyborg things that move the plot forward.
As a child, I was blessed to grow up in New York City. Our local PBS affiliate got the newly released Doctor Who shows only a few months after they aired on the BBC. For all intents and purposes, it was the closest any American audiences got to seeing the episodes in "real time" in the dark times before the advent of the internet. As a result, I was exposed to the Doctor at a very young age. My Father had been a Sci-fi fan for many years, and would insist on watching the "new" episodes of Doctor Who as soon as they aired. (and Blake's7- the guys at the PBS station were hardcore anglophiles before that was a word) In that far bygone era (I feel so old) we only had one TV like most middle class families, with like five channels, so whatever the master of the house wanted to watch, you watched.
So it came to pass that at the tender age of 6 years old, I watched "the Ark in Space". While my Mom chittered at the special effects and my Dad explained the idea of the Tardis to me, I got scared out of my little mind by the idea of giant bugs from outer space that were coming to transform me into little crawly piles of green goo.
Yes, I was behind the couch the second that big Wirm fell out of the closet. I still have issues with bugs,(Thank you, Director Rodney Bennett, for a lifelong phobia) yet my Stepson wants to be an entomologist. Fast forward to forty or so years later, when my kid started watching Doctor Who with me. I was concerned that the "behind the couch" effect wouldn't be the same for todays jaded youth, and I was right in that the boy found the Daleks and Sontarans funnier than scary.
Then he watched "Silence in the Library" with the Vashta Narada, and in a flurry of terror that leads to the back of the couch, another generation of my family "Gets" the Doctor. If my own fear of bugs is any indication, I have no idea how he'll ever be able to take his own kids to the library.