Too uneven in tone and style to be memorable.

Rating: 6/10 (5 October 2014)

The elephant in the room is The Princess Bride, to which Stardust compares poorly. There are many ways to make a fairytale-romance movie, and rats of unusual size need not feature, but Stardust gets it so inexcusably wrong on so many levels that you can't help coming back to "Princess Bride" to show how its done.
Which is a shame, because there a lot of good elements here, some great cinematography, and some first-class special effects / set design. One of the few instances I can think of where the witches' magic spells actually feel dangerous. The casting is solid, and the acting is nothing if at least good-natured.
So what went wrong?
With a fairly tale, the cardinal sin is winking to the audience letting them know the characters know its all a big joke. The characters have to take themselves and the story - the risks, the danger, and the emotional investments - seriously. The silly stuff (i.e. rats of unusual size) can be silly, but only to the audience. The characters must behave as if those rats are really dangerous. That's part of the fun.
Stardust strives for a similar mix of humor and emotional weight, but 1. there's very little actual wit, just sight gags and slapstick and 2. no one seems to take anything seriously. Certainly not Robert De Niro or Michelle Pfeiffer. They are clearly having way too much fun chewing scenery to care about what happens Yvaine and Tristan.
That's problem one. Problem two is the story. The concept is basically fine, I'll accept the basic premise that there's this magical world you can get to from just outside an English village, a world with evil witches and unicorns and where stars fall to earth as young women. If that's the conceit, fine, let's run with that. And I'll accept that there's a king who has seven sons all out to kill each other over the inheritance. And, sure, lets add in a flying pirate ship that collects lightning. No wait. A flying pirate ship, which isn't actually doing anything piratical, since, I mean, they are just out there harvesting lightning for some reason. I mean, wouldn't they be more like fishermen? And why would people want to buy the lightning? What can you do with it? And why do we never see any other kind of flying ship? Why is everyone else traveling by road, by horse, even the king's sons? I mean if lightning harvesters can have flying ships, you'd think the king would have access to cool flying dreadnoughts or something.
And while we are at it, what's up this enormous kings palace, at the center of a city which looks to hold hundreds of thousands of people? Why is it we never meet anyone from there, outside of the kinds son's and one or two attendants? Until the last scene that is, when suddenly there's a football stadium filled with people! And if there's this clearly large, prosperous, and powerful city - what is their relationship with the witches? They would seem to be a nuisance, why wasn't there a war or something to get rid of them. What do the people do all day? And if there are unicorns, are there dragons? Why not? And what happened to that unicorn anyway?
The movie does a very poor job of convincing you the world it wants you to believe in actually exists. It's like no one thought it through, even superficially.
All nicely rendered/shot, mind you, just totally unconvincing as a unified, functioning world.
Finally, the last complaint, which concerns the traditional flow of a fairytale. Yes, we know roughly how things are going to end. But a fairytale is about the journey where the hero proves to us he is deserving of getting the girl, the gold, and of living happily ever by being both smart and good. The point is there are challenges, puzzles, riddles, and often actual suffering, which by overcoming the hero both learns some important lessons and proves his worth.
In Stardust, Tristan never proves his intelligence, resourcefulness, or moral fortitude in the face of need. He's given two incredibly powerful magic items by his mother. He's taught how to fight by Captain Shakespeare - for no especial reason, there was nothing he did to deserve the special treatment. And Yvaine stepped in to save him in the final battle with the witches. Basically anyone could have taken his place and done just as well, it was a cakewalk.
I think that's the most irritating thing with this movie. For all the great special effects, and cool cinematography, and can-can dancing, the vital elements which make a fairytale work as a fairytale got left out.