I'm not going to say anything about Obama's plans, policies and centrism/socialism right now, because I'm willing to give him a bit of time to show his true colors, and judge what he does (or doesn't do) on its merits in due time.
But there is an important point to be made right now: this election puts an end to the horrible Bush administration, and presumably puts an end to incompetence, profiteering and cronyism (although we'll have to see what the outgoing administration does in the next 2 months) but it does not put an end to the consequences of what the Bush administration has done. What has been broken is not magically repaired just because the guilty party is removed from the scene.
Some of what was broken can be repaired, with time, effort and good policies - like the economy, global climate change mitigation efforts, or the competence and neutrality of various government agencies, and the abuses or simple pigheadedness of the Bush years can simply be stopped.
But other things cannot simply repaired so easily. The rule of law was broken repeatedly, both in the USA and outside it, with no apparent consequences. The trust in America as a benevolent actor on the world stage, already tenuous at times, is now irredeemably destroyed, and will not come back simply because Obama is the new president. America is now irreversibly the country that had torture as official policy. It is the country that has invaded other countries on false pretenses, against the rules agreed in the UN and against the wish of major allies. It is the country that only accepted as friends those countries that agree with it, and demonised those that did not. It is the country of Guantanamo, Abu Ghraib, FISA, ignored subpoenas, etc...
Stopping all of this, as is most likely to happen, is a good thing, will not undo what has been done.
Changing the present requires new policies, and there is a decent chance we'll get them. Dealing with the past requires justice and atonement, and I have no idea if we'll get that. But it will also be part of whether Obama is a good president or not, ultimately, even if it seems less urgent than dealing with the economy, healthcare or Iraq.