I've heard only good things about the Mekensleep-developed, Eidos-published title, Soul Bubbles, yet I haven't added it to my DS collection.
That may have to change now that I know the game includes two bonus levels done in the ukiyo-e style. (According to wikipedia, ukiyo-e is is a genre of Japanese woodblock prints and paintings produced between the 17th and the 20th centuries that feature motifs of landscapes, tales from history the theatre and pleasure quarters.)
Yes, I'm a sucker for ukiyo-e. Sadly, few games feature graphics inspired by this style--in fact, the only one I can think of right now (other than Soul Bubbles, of course) is Konami's ancient arcade title, Mr. Goemon. (Goemon's one and only DS outing features the similar sumi-e style, as does Ōkami and its forthcoming sequel, Ōkamiden.)
Speaking of awesome art styles, I'd have to slap myself if I failed to point out the cute-as-hell box art created for the Japanese version of Soul Bubbles, known as Awatama:
In a perfect world, I'd pick up a copy of Awatama instead of Soul Bubbles, but as of now the former costs about three times as much as the latter ($48.90 compared to $13.87).
Buy: Awatama or Soul Bubbles