I really enjoyed it and I think it works better on a rewatch. It still has that third act problem, of course. Miyazaki still isn't a narrative-driven writer. This time, though, I'd got deeper into the characters and I thought the third act was okay. It's a bit messy (e.g. the time-slip back to Howl's childhood), but I managed to stay on board. One day I'll give it a third viewing and see if that raises my estimation of it even further.
Original Diana Wynne Jones novel: 1986.
Hayao Miyazaki's fairly loose adaptation: 2004.
Plot outline: Sophie is the oldest of three sisters in a magical fantasy steampunk world that's fighting a war. The historical era looks a lot like the 1910s, so we can probably take it to be World War One even if Sophie's a long way from the front lines. One day the Witch of the Waste comes to Sophie's hat shop and gives her a present. She makes her older and wiser. A lot older, in fact. Sophie's now about seventy years older than she used to be.
There's a lot to admire here, I think, starting with Sophie herself. Dumpy old granny heroines are something you just don't get, normally. She's great! This is as near as you'll ever get to an Old Lady Fantasy Heroine Movie, in fact, with the most important characters being Sophie, Suliman and the Witch of the Waste. My favourite scene in the film is the Old Ladies' Race Up The Stairs, partly because that's where Sophie proves to be more forgiving than one expects in fairy tales.
Our heroine busts all kinds of stereotypes, including the one that "evil is ugly and good is beautiful". Sophie thought she wasn't pretty even when she was young. Similarly the narcissistic Howl has a literal meltdown (into green slime) when he dyes his hair the wrong colour, the antagonistic Suliman is looks charming and elegant and the Witch of the Waste ends up becoming a hideous barely human blob and yet also adorable.
The character work tends to skip over things. Sophie falls in love with Howl in a sleight-of-hand way that you've got to take for granted. We don't see it happen. After a while it's just sort of there. Similarly there's a character arc to the film's third act, but it's a bit chaotic and it takes some effort to follow it. On first viewing, a bewildered viewer might almost take it as rubber reality.
Mind you, at least one's usually getting the sense of a narrative in the first place. It's adapted from a book. Spirited Away and Princess Mononoke have a random "what the hell" quality. They're bursting with imagination and charm, but they're also liable to flail all over the place.
All that said, though, the film's also a gorgeous experience. The moving castle itself is a Monty Python delight, with lots of non-moving bits that heave and breathe all over the place. I love the cars in the capital city. I love the scarecrow. Boiling this film down to its plot is to miss the magical world it gives you. At the same time, though, it's also a remarkably dirty world, with both the moving castle and the steam-powered local technology being smoke-belching monstrosities. I'm reminded of the environmentalism of, say, Princess Mononoke. There's something oddly exhilarating about all that bombastic steampunk and its unashamed pollution, but it's clearly dirty as hell. (Miyazaki has always understood the excitement of, say, war planes even as he disapproves of their intended use.)
It's effectively a Beauty and the Beast story, but subverting both of those elements. (People becoming monsters is another Miyazaki thing.) It's funny. I loved the fire demon. It's full of imaginative touches, like the blobby walking-oil things. I think Miyazaki could have used a co-writer to point out when the storytelling was taking short cuts and the male characters (like Howl!) were being short-changed, but I also think it's a deceptively deep film that will reward close study and attention. Plus, of course, it's just a lovely experience.