If you like your series to have top-notch special effects, you might not like Doctor Who.
That's the only possible reason for disliking it, though. It's the only flaw that the entire series, from the first ever episode on the 23rd November 1963 to whenever you're reading this, actually shares. Everything else comes and goes. To me, saying that you don't like Doctor Who is like saying you don't like fiction. Are you sure? There's quite a lot of it.
Doctor Who is a franchise so massive it would be a lifetime's work trying to experience it all.
It ranges from comedy (City of Death), to romance (The Girl in the Fireplace), to violence (Vengeance on Varos), to so-bad-it's-good (The Chase), to cosy family viewing (The Christmas Invasion), to 'proper' science fiction (The Ark in Space), to the downright weird (Ghostlight)... I could go on for some time, and that's just the TV stories.
On top of that, there are hundreds of books (from the more adult-orientated Virgin, EDA and PDA ranges to the child-friendly modern BBC releases), hundreds of audio dramas and countless comics.
If you can think of a medium for storytelling, you can be pretty sure that there will be Doctor Who stories produced in it.
You might not like the new series - fair enough, there are still 40+ years of Doctor Who you might like. You might not like watching things in black-and-white - fair enough, there are still 39+ years of Doctor Who in colour. Plus all the aforementioned books, comics, audios etc.
It's almost ridiculous to try and talk of Doctor Who as a whole because there are no traits that apply to the whole of it.
There are reasons to criticise any era of Doctor Who, from excessive violence to excessive moralising to excessive romance. But, please, if you've only seen a couple of episodes from the same producer and didn't like them, try something else. This review may seem very apologetic rather than enthusiastic, but just as the whole series doesn't have the same flaws, it doesn't have the same strengths.
That's why, in the words of Russell T Davies (producer 2005-2010), it's "the best idea ever invented in the history of the world." It's fabulous and funny and scary and thrilling, but, above all, wonderfully, brilliantly varied. And very highly recommended.