Stardust definitely felt like Stardust. It captured the feel and spirit of Neil Gaiman's work as much as it possibly could.
Some cuts were made even though the original book wasn't even half the size of the average Harry Potter book. I liked that the movie cuts right to the chase, beginning with Dunstan and Una's first meeting. (Dunstan deliberately trespassing over the Wall to go to the Fair created a nice father/son parallel with Tristan.)
The cast was very good. It was a smart choice to cast an unknown as Tristan; Charlie Cox is sweet and fits the part, like Orlando Bloom without the blankness. Claire Danes is a very spirited Yvaine. The special effects that show Yvaine literally "glowing" with happiness were cheesy but cute. Septimus was a lot of fun. The dead brothers made an amusing Greek chorus. I loved Rupert Everett's dramatic introduction and immediate execution.
On the negative side, I wish Captain Shakespeare wasn't such a blatant Dues ex Machina...or such a broad stereotype. You can tell that the filmmakers were hoping he'd be the breakout supporting character, like Inigo Montoya without the vendetta or Jack Sparrow without the sexual ambiguity. It doesn't quite work. Outside of his collaborations with Stephen Merchant, I don't think Ricky Gervais is funny. So while his part dragged on for too long, it was kinda cathartic to see him silenced and then killed.
The previews worried me; I thought all the clips of sword-fighting meant that they'd turned it into an action film, but I was pleasantly surprised. There was an action-y climax, but it wasn't without sparks of creativity (Septimus as the corpse-puppet).
One element I really disliked was the treatment of Victoria. In the bookI know that the movie had to make some shortcuts when telling the audience that Victoria isn't right for Tristan, but they took the predictable route and made her shallow and catty. The movie's last jab at her, which hints that her soon-to-be-husband is secretly gay, seems downright mean-spirited.
I did enjoy the altered ending. The original book is meant to be an adult fairytale, so works. The movie's ending is more traditionally happy (Dunstan and Una even end up together, even though their previous relationship was just a one night stand) but it doesn't feel strained. Considering the genuinely fun, whimsical tone of the movie, the "and they lived happily ever after...literally forever" ending was the right one.
"As I bit into the nectarine, it had a crisp juiciness that was very pleasurable, until I realized that it wasn't a nectarine at all, but a HUMAN HEAD."