The grayed out text is (of course) a feature... there's less text on the page in the landscape big text mode, so it helps give you context between pages. I used to have a problem on my Treo because I would lose track of the sentence between screens and have to flip back and forth to catch up again.
But one could also argue that it takes up precious real estate and is a nusiance to read grayed out text also.
I haven't tried it enough myself to know which I like better yet. They gray is nice in theory, but in practice I'm not so sure...