Sharon B from pintangle did a great review of the site on her blog (permalink to the article. )
Her blog entry goes through step-by-step of how she made this tulips chart, and is a great into tutorial for how to use myphotostitch.com to make a cross stitch pattern. The one thing she didn't mention was that the Advanced Form has more options than on the Basic Form, which she used in the tutoral. Specifically, you can choose a custom pattern size, not just one of the predefined sizes. You can also choose a variable number of colors, and enhance the image or dither the image, which may help produce nicer results. Check it out
Her description of this image and pattern: "I used this image in a review of MyPhotoStitch on my blog. You can see the review on http://www.pintangle.com/"
Go check out her review and her blog for a bunch of stitching, embroidery, and other crating articles. Scanning her site, it looks like she spends a lot of time finding and posting interesting things.