hmmm... such a broad request - I'll answer in broad terms.
Iraq - whatever your feelings are about the "traditional" allies france, germany, russia they provide a huge deal of muscle on the international stage and now they are substantially less willing to come to the aid of the the United States due to our actions in Iraq. Regardless of your opinion about the Iraq war being just or not, you cannot deny that it has significantly affected relations between the United States and a number of other countries.
Social Security - the 2000 debates revolved around putting the SS surplus in a "lockbox". Bush promised not to touch it. Within 1 year of taking office, Bush began to use this money to prop up the budget numbers thus making the insolvency of the institution approach that much more quickly.
The environment - Generally, most scientific research has been disregarded by this administration with respect to the environment. Scientific American had a great article about 2 months ago condemning the administration for it's distortion, disregard and even outright manipulation of science for its ends. As far as I know, SA is not typically regarded as a partisan publication. Specifically, I would note that deregulation of environmental regs on power plants, clean water and the attempts at opening public land for resource explotation are prime examples of damaging the US institution of conservation as envisioned and established by Theodore Roosevelt.
Immigration policy - Explain to me how the lunacy of bush illegal immigration policy makes sense? Allow anyone who slips over the border illegally amnesty, while people who go through legal channels and wait years for entry into the country get nowhere. Take about encouraging illegal immigration.
Tax cuts - whether you agree or not for a tax cut, Bush originally intended the tax cut to return the budget surplus to the people, but when the economy tanked, the tax cut was to improve the economy. I cannot understand how the tax cut could be justified as improving a bad economy if it is demanded in both a good and a bad economy. It simply appears, that yet again, Bush is concealing his true intention. He wants to give a tax cut regardless of the status of the US economy, but uses the bad economy to justify it. I will also say that I am NOT opposed to a tax cut if it is fair across the board and the intentions of the tax cut are clear - ie; returning a surplus to the people. It is not, however, in my opinion, a valid tool for reviving a soft economy. I particularly am angry because I will be paying the interest on all the money borrowed by the Bush administration to support the tax cut for years to come. Fiscal discipline means cutting back spending and increasing income, not spending more and taking in less income.
I could go on, however I need to work to afford to support Bush's absurd wastes of money.