The most recent issue of Foreign Policy magazine raises the thought provoking or perhaps shocking assertion of "Why you'll miss him [George Bush] when he's gone". Although it is easy to hate and revile all that is Bush, even the staunchest detractor can find some common ground in which to miss him (or ground in which liberal-leaning, e.g. Bill Clinton was a great president, history will vindicate him). Below I detail two such examples.
On September 11, 2001 the United States homeland was attacked. This event decisively ended a 12-year period of relative peace and ushered in a new era in which the enemy was Transnational Terrorism. The majority of US citizens called for action while the president responded.
In this situation, the commander in chief's hands were tied; be that individual Bush, Gore or otherwise, she/he had to respond to this 21st century Pearl Harbor. If we consider the past, it is hardly the president writing history but more the president reacting to history. In 1916 Woodrow Wilson won reelection on the slogan of "He kept us out of the War". April 6, 1917 the US went to war. In FDR's reelection campaign of 1940 he promised to do everything possible to keep the US out of The War. December 8, 1941 the US declares war on Japan. During Nixon's 1968 election campaign he promised that the "new leadership will end the war and win the peace in the pacific". Rather than scaling back the war it later reached new heights. (To this we can also add Obama's promise of "Out of Iraq" to what will in actuality be a long slow draw down, assuming he is elected.) The conclusion here is that there are limits to presidential power and that the War on Terror was unavoidable. Therefore, we are left with the difficult question of, How has Bush handled the war?
The War on Terror
Once the inevitably of war is accepted, we can focus on and see that Bush has done well on a number of points. Most successfully, in Afghanistan and elsewhere, Al Qaeda's operational capabilities are hamstrung. Although Osama Bin Ladan still remains at large, empirically we have seen that Bin Laden has been unable to orchestrate an attack since September 11, 2001.
Beyond Al Qaeda, general terrorism has been struck a hefty blow too. To answer the question, "Are we winning the War on Terror?" the answer is certainly yes. (Can you really argue no?) This war is not one which will have decisive winners and losers, though progress can and has been made.
Geopolitics of the Middle East and Iran
Whereas the War on Terror was a done deal, the invasion of Iraq was dictated in large part by Bush. Thus, to examine Bush's general success in the Middle East we must compare: (1) How things look now to (2) how might they have looked had there been no invasion. (Though we can not assume that Gore wouldn't have authorized some sort of invasion of Iraq!)
The important issue which is and would have been the focal point of the Middle East is nuclear Iran. With the invasion of Iraq, thousands of US forces were stationed within easy operational distance of Tehran. Despite the troops being occupied, the US held an important strategic capability which the Iranians could not overlook. Furthermore, simply by being in Iraq, Bush demonstrated his clearly hawkish tendencies, which undoubtedly influenced the Iranian thought process. Although it is may only be happenstance, Bush has found success in keeping a check on Iran while only threatening the specter of US incursion. Had there been a different president and without an invasion of Iraq there would have been more diplomatic wrangling, multiple threats of force, and ultimately a measure of success perhaps equivalent to what exists now. Though to expect a fully brokered disarmament and peace deal is too much to wish for. Bush has done comparatively well in regards to Iran.
In summary, the "Lonesome Cowboy" (or unilateralist attitudes) of the Bush presidency have had some lasting benefits. The War on Terror has been a success (as measured under the reality that military force would have been used) and the controversial invasion of Iraq has been a boon to keeping Iran in check. It may be a stretch to say that you will miss Bush, though to denounce his two terms in their entirety is to fall victim to irrationality.