I'm not entirely sure I can explain what it is about the new Dr Who that irritates me so much. Still, I'll have a stab at it.
1) First Christopher Eccleston and now David Tennant play The Doctor in an annoying "I'm mad, me!" fashion.
2) Billie Piper's acting ranged seems limited to either smiling at inappropriate moments or else crying whenever she thinks her mum/dad/Mickey are dead or are about to leave her.
3) The attempt to sex up the series by having nearly all the female characters fancy The Doctor feels forced. And his relationship with Rose feels kind of creepy.
4) Trying to make The Doctor cool by making him a fan of the Sex Pistols and dressing him in designer clothes is just plain embarrassing.
5) The incidental music is always completely OTT in a desperate attempt to convince the viewer that what they're watching is really dramatic, honest.
6) Every damn story is set on Earth. Even Jon Pertwee's Earth-imprisoned Doctor got to travel the cosmos more than this.
7) The emotional climax at the end of each episode drags on forever. Nearly every week the threat has been dealt with, all that's left is for Rose and The Doctor to hop in the TARDIS and the end credits to roll. Instead you get five or ten minutes of soap opera style hand-wringing. "Oh, I'm really upset that so-and-so died! Sob!" "Oh, I'm going to have to leave behind the person I love. Sniff!' Emotional payoffs should either be tied into the dramatic climax of the main plot or else handled quickly in a brief epilogue before Rose and The Doctor go traipsing off around the universe once more.
8) By trying to round out the supporting characters (a good thing) the writers reduce The Doctor to a deus ex machina (a bad thing). Often he only seems to be there to supply info-dumps and to wave his sonic screwdriver about whenever Russell T Davies has written himself into a corner. Otherwise I get the impression that Rose would be saving the universe by herself each week. Even when The Doctor does get something to do it tends to either be a badly choreagraphed action scene or else an embarrassing emotional scene.
9) The humour is too broad. Even when the basic jokes are funny the execution lacks wit and sparkle.
10) Most of the stories have plot-holes you could drive a truck through.
I could go on but I've probably already got every Dr Who fan in the UK baying for my blood. I suppose if I had to sum up my problems with the new Dr Who it's that too often it feels like a soap opera -- Eastenders with a couple of sci-fi flourishes added on.
Obviously I'm not saying the old Dr Who was flawless. I could probably make a list of its faults that would be just as long as the one above. (Actually it would probably be rather easy to stick the boot in to the old series as about 80% of my childhood nostalgia for Dr Who comes from reading the Target novelizations rather than watching the TV series.)
And the new version is obviously very popular, pulling in loads of viewers and even convincing the BBC that maybe they should make other sci-fi series. Hell, even I find myself enjoying bits of it. But as the new version is so popular -- winning BAFTAs and everyone saying how wonderful it is -- I felt it was worth pointing out that in certain respects it's actually pretty crappy.