I'm a little worried by the overwhelming emphasis on exploration of habitable places -- Mars, Europa, extrasolar (plus the Moon as a convenient training camp).

Personally, I'd rather see a more broad science focus. At Mars, for example, I'm as interested in the geologic story as whether or not it had bacteria on it in the distant past. And I think there's just as much interesting stuff to figure out at Venus (though it'll be much harder to do so with current technology, so a Mars-first approach isn't totally unreasonable). Hell, Venus was probably a better candidate for early life anyway, though good luck finding exposures of 3 billion year old rock.

Not to mention comets and Kuiper-belt objects, astrophysics, etc.

Even in terms of Mars, I'm a bit leery of loading all the eggs into the astrobiology basket. If in ten years life looks unlikely on Mars as its distant past appears less and less warm and wet (it's all Nick's fault!), that'll take away much of the rationale for going there. As the political cynic here I realize that "life" is what sells, but as written this plan goes farther than is necessary, I think.

On the other hand, the budget table in the back shows that "aeronautics and other science" funding levels stay constant, so maybe this doesn't hurt space telescopes or asteroid missions or whatever.