It's very much a Disney film - and in purer form that I've seen in a very long time. I can't quite call Hidalgo a comedy, but in tone it reminds me a lot of the 1965 version of That Darn Cat! or the 1971 Bedknobs and Broomsticks. The villains are dastardly, the heroes are flawed but still have a certain purity, the heroines are plucky, and the odds are triumphed over.
Now, I have a huge soft spot for 1960s & 1970s Disney family movies - probably because those were about the only movies we were allowed to watch - so I don't mind. I don't care if the story of Frank T. Hopkins is true, false, or somewhere in between. But I can certainly understand why the film reviewers at the major US dailies wouldn't agree with me.
So I'd just say that if you see it, see it in the proper spirit and you'll probably enjoy it. Go in expecting Angstful High Art or another LOTR, and you'll probably be sad.