Now perhaps that the answer is likely to be "sadly, no," George Will no longer wants to hear the question: "are you better off than you were four years ago?"  In all fairness, his problem is McCain's use of this very Reaganite phrase.  When Reagan used it, of course, it made sense:

The nation considered the answer obvious. Reeling from oil shocks worse than today's, with 52 U.S. hostages in Tehran and with the Soviet Union rampant in Afghanistan, voters resoundingly said no. Today we know that the Soviet invasion of Afghanistan hastened the collapse of the Evil Empire, so some things that seem to make us worse off are not unmixed curses.

Take heart America, look on the bright side.  In Will's defense, there are any number of reasons to reject this particular political device.  I might say in the first place that McCain looks like a fool asking it, considering his the Republican candidate for President.  As Will points out, it's a fairly vague question, but I would say that's its rhetorical, not logical, appeal.  Here is, however, one reason not to reject it:

The people asking and those answering the "better off" question seem to assume that the only facts that matter are those that can be expressed as economic statistics. Statistics are fine as far as they go, but they do not go very far in measuring life as actually lived.

No one really assumes that economic facts are the only relevant ones.  And it also would be supremely  disingenuous to suggest the question ought to consider the accumulation of good memories:

Suppose in those years you read "Middlemarch," rediscovered Fred Astaire's movies, took up fly-fishing, saw Chartres and acquired grandchildren. Even if the value of your stock portfolio is down since 2004 (the Dow actually is up), are you not decidedly better off?

Sheez.  Most people hearing that question would assume its non of the asker's business whether they've had a good time in their personal life these past four years.  But what looked initially like straw man in its misrepresentation of the question, now turns into an excursus on the meaning of life, David Brooks style:

We do, unfortunately, live, as Edmund Burke lamented, in an age of "economists and calculators" who are eager to reduce all things to the dust of numeracy, neglecting what Burke called "the decent drapery of life." In this supposedly rational and scientific age, the thirst for simple metrics seduces people into a preoccupation with things that lend themselves to quantification.

Self-consciously "modern" people have an urge to reduce assessments of their lives to things that can be presented in tables, charts and graphs — personal and national economic statistics. This sharpens their minds by narrowing them. Such people might as well measure out their lives in coffee spoons.

So now if you care to consider your economic status now versus four years ago, you measure your life in coffee spoons?  Now it's a false dichotomy: you either consider your reading of Middlemarch, your grandchildren, and baseball fandom have made your life better (despite your home foreclosure and costs of medication), or you are an economic reductionist.