Old Fans Never Die...
The shame is that they got the whole Doctor Who/Torchwood approaches the wrong way round. Since Doctor Who already had an established fan base in or around their 30s, I reckon they'd have done better to treat the new Who show as the 'adult' programme and aimed Torchwood at the kids.
Mind you, even then we'd have to face up to the fact that Torchwood was more adolescent than adult: throwing in lots of gratuitous sex references (of any orientation) doesn't make an adult programme. It's a shame RTD didn't wait until after the new Battlestar Galactica showed what adult sci-fi *really* looks like. Torchwood at its best can't hold a candle to BSG at its weakest. I'd say the same for Doctor Who except it does get a little redemption from the episode 'Blink', which was frankly genius. Having the Doctor as a mysterious background character, barely seen while influencing the lives of others, made for a far more interesting story. 'The Girl in the Fireplace' was pretty good, too. But in general the new stories have been really weak - too much focus on ancillary characters and bloody Daleks. And it's a shame we never explored the Doctor's back-story more.
Still, I do rate Eccleston and Tennant as the Doctor - I think they both did an excellent job, and without wanting to be unfair to this new guy, who hasn't actually had a go yet, I think the makers of the show went in the wrong direction. Aside from the opportunities they had to try something contentious - a black Doctor, perhaps, or a female - I think they're missing out by focusing on Young And Attractive at the expense of Mature And Interesting. (With due respect to any readers who might be young and attractive and interesting, obviously.)
I've tried very hard to be a fan of the new Doctor Who, out of established loyalty to Tom Baker through to Sylvester McCoy; but I think when David Tennant leaves it'll be time to give up.