Elmofongo: I don't even know who Dr. Who is and whats his appeal?
It's many things. An old cheesy series for british families, based on unapologetic (and traditionally forgiven) cheap effects, varying doses of educative content (time-travelling history education was originally the plan, got ditched out the window half-way through the first episode's first minute though), humour and suspense or horror (mostly aimed at scaring 5 years old, but still).
Plot-wise, it's the adventures of a quirky, eccentric, wise, kinda immortal, super scientific from outer space, who travels in a time machine, gets spotted by some human or another, who ends up travelling with him like a holmes' watson through various dangerous adventures mostly involving running away from monsters and saving worlds. And by worlds, they generally mean London. And by London, they generally mean the BBC studios and its cardboard props. It was a long long long series, and many different actors have played the alien hero, a bit like the different actors playing james bond, except that, there, the change of actor is explained in-universe : when he is about to die, the hero transforms into a new character, who is the same at the roots, but looks different, has a different style, and plays the role in a different tone. Like an insta-reincarnation, if you will.
It went on hiatus for several years, and got resumed in 2005, with a more modern approach, in terms of effects and cinematography. Became very watchable (though the fans claim it already was). It has a very specific style, a very peculiar balance between family-friendly, freaky, self-aware, ridiculous, humorous, actually weirdly suspenseful and even quite moving, at times. Globally, it doesn't take itself seriously except when it does. It takes a specific mindset to watch, and really benefits getting into it chronologically, following its over-arching plots and characters-development. It's also, ideologically, a bit heavy-handedly progressive, but I like this aspect. In a time where badass murderous ex-marine gritty heroes are the norm, it's nice to see the adventure of a brainy sarcastic pacifist with chievalrous values to the extreme. In that sense, the Doctor is very close to old super-ethical, morally "pure" heroes, like Tintin or Bob Morane. And, the writing being quite intelligent, all his traits (his superiority, his moral constraints) are being lampshaded, questionned and deconstructed within the series.
So, it's good stuff, clever, self-critical. Benefits from a "traditional" cult aura in Great Britain, given its longevity and careful family-friendliness (aimed to be watched by kids, parents, grandparents together, without boring anyone). And got plagued by several by-product trying to exploit some of its aspects at the expense of others, and failing more or less miserably (Mary Jane Adventures aimed exclusively at children, Torchwood aimed excusively at teenagers who want to feel like grown-ups, etc).
It's worth trying to get into the specific mood it requires. Because it's an original show, with a tone, universe, style, unlike others, and this at least is always refreshing, whether it fails or succeeds at what it tries to be.