Of course plenty of people will disagree- myself included, based on my experiences with American cartoons. A written or drawn character has more room for interpretation (i.e. imagination), and one person's vision (particularly regarding voices) does not match another's.
Also, even Japanese directors are limited by their budget, which limits which actors they can get (due to price, availability, and interest). There's no guarantee the Japanese voices fit the director's (not to mention author's) vision.
Some humor and meaning may be lost in the translation, due to cultural differences, but a good (and I mean very good) translator should be able to find a similar joke or reference that will be funny to the audience. And, not being Japanese, some meanings are lost on us, anyway. But on the flip side (there's usually a flip side, isn't there?), we're also a little less tuned-in to weaknesses that may be in the story, because of our unfamiliarity with the language and culture.
So, it's mostly up to the quality of the team dubbing/translating, and we've yet to see much really good dubbing.