Howl's Moving Castle (IMDB 8.0|Rot 84%) (DVD Rental)
I liked Castle, but it pales in comparison to Spirited Away (IMDB 8.5|Rot 98%) and Princess Mononoke (IMDB 8.3|Rot 92%). All of these are Japanese animated films, directed by the same (brilliant) guy: Hayao Miyazaki.
Castle takes place in a magic steampunk world. Sophie, a hatter, gets caught up in a bit of magical intrigue causing her to search out Howl, who lives in the eponymous moving castle. Besides being ambulatory, the castle's front door exists in multiple places at once. Add a talking fire, a non-verbal but helpful scarecrow, a little kid, and animal transformation and stir.
The sadly miscast English dub was alternately flat/unaffected and overacted. I eventually switched it to Japanese (English subtitles) so I could at least understand the character's emotions.
The story largely makes sense from moment to moment (and all of the moments are interesting), but the overall arc barely holds together. The ending has a giant and unwelcome deux ex machina; I would have preferred the thread to have been left dangling instead.
Like anything by Miyazaki, it's worth seeing. However, if you haven't seen Spirited Away or Princess Mononoke yet, see them first.