There were some lovely sets/costumes in classic Who. Parts of Planet of Evil really do look like an alien jungle (of course other parts look like a studio because they had to shift into the studio for bits) and things like Zygons or the robots from Robots of Death could almost step into nu Who with little or no modification (actually you could even argue the original Sontaran makeup was pretty darn good as well.) and beyond Who the Liberator flight deck from Blakes 7 is a gorgeous set. The trouble is for every brilliant bit of work done, they did something that hasn't held up nearly as well, or worse something that was terrible even at the time, but even if their reach sometimes out did their grasp, at least they tried, and seriously what would you prefer? sailing ships in space or farting aliens?
I've been watching old Doctor Who recently and I'm surprised at how much of an emotional core it does have; it's just very differently done than the current Doctor Who. In regards to the writing it's tough to say as you're comparing very different things but there's a lot of smart Doctor Who that occurred between 1963 and 1989. I quite love new Doctor Who but in terms of a sharp, witty, scathing script I don't think anything has undone "The Caves of Androzani." Really couldn't care less about the visual effects, to be honest.
Some people will never accept that anything in classic Who was the equal or better of anything since 2005, in the same way there are people who won't aknowledge that in many ways Nu Who is superior.
Gareth Roberts has summed it up nicely. There are plenty of places the new series has gone that classic Who wouldn't/couldn't, but by the same token lots of areas that classic Who touched upon, the new series wouldn't be able to touch with a barge pole now. (I need to get home to my copy of the Brilliant Book of Dr Who for the exact quote).
Classic Who is better sometimes, Nu Who is better sometimes, it depends. It's like pacing. A lot of old stories were too long, too full of padding, but often they worked really well, allowing a story and characters time to breathe. The new series is a lot pacier, but there have been plenty of episodes where you wish they'd had a little bit longer to tell the story, to generate some drama or tension or make you care about the guest cast.