I don't know enough to speak intelligently on the subject, but I couldn't find any reason that we should all completely disregard her visions.
The bible talks of people being given visions by the Spirit. Who's to say that she wasn't given one of those visions? The writings I found of hers (quick glance, I probably read a page or two of her own material. There seems to be thousands of pages more that she wrote during her life) seemed to be in line with many other people who claim to have been given visions. Most noticeably the fact that nearly all believable claims of seeing visions of Christ are of a formless light, too bright to stare at, which is immediately known to be Christ even without words.
Her teachings of health don't seem to be too far out of line from normal Victorian era views on the subject. Eat well, drink water, be active, go outside; none of these were ground shaking ideas at the time. The only thing exceptional about them was that she called them revelation.
It is a very interesting topic. I'd love to see other people's views on the subject.