Bush's presidency was one of the worst of all time. The most obvious reason is that he invaded another country for no legitimate reason and enmeshed the U.S. in a costly militaristic quagmire and civil war. But that is not the most important reason. Worse, Bush tried to expand the powers of an already imperial presidency to a breathtaking extent - severely undermining the balance of power among the branches of government enshrined in the Constitution and riding roughshod over the civil liberties of American citizens and foreign nationals alike. In addition, the increase in domestic spending during his term was the largest since Lyndon Johnson.
He advocated bad policies and demonstrated horrendous operational incompetence. The disastrous and expensive (in casualties and money) nation-building projects in Iraq and Afghanistan were only exceeded in catastrophic results by Bush's expansion of executive power and theft of the civil liberties that make the United States unique. Bush had almost no accomplishments to offset such policy foibles. Bush was thus one of the nation's worst presidents. But he was not the worst president the United States has ever had because James Polk, William McKinley, Harry Truman, and Woodrow Wilson presided over wars or Cold Wars with even more pernicious and dangerous effects.
Bush's gargantuan bailout of the financial industry, which could cost taxpayers 2.3 trillion dollars, entailed unprecedented government intervention in the country's financial system and another expansion of executive power. It brought the U.S. closer to socialism - the nationalization of private companies during peacetime - and Mussolini-style corporatism - with the government owning shares in the troubled firms. Lastly, the bailout involved welfare for the rich, as the government acquired the authority to buy bad debt en masse. Like Herbert Hoover, Bush flooded a market replete with credit with even more credit. This move will likely exacerbate and deepen the global financial meltdown that was caused by many financial institutions' risky loans, and which were encouraged, among other factors, by earlier bailouts.