The Obama administration has deported close to one million undocumented immigrants since January 2009, according to recently updated statistics from Immigrations and Customs Enforcement.
Since fiscal year 2009, the actual number is 1,107,415. But the financial year started in October of 2008, when George W. Bush was still president, so the total under Obama is actually 982,548. On the other hand, the current numbers only go up to the end of July, so the administration may have already passed the one million deportations threshold. By comparison, in his last 28 months in office, Bush deported about 785,148 undocumented immigrants. (I couldn't find monthly records for before 2007.)
How you react to Obama's record on deportation depends where you are on the political spectrum. The GOP has been accusing the administration for months of instituting "de-facto amnesty" even as deportation numbers skyrocketed, while liberals and the Spanish-language press have been attacking the administration for breaking its promises.
Last month the administration finally indicated it would be deferring the deportation of undocumented immigrants who pose no threat to public safety, but in the absence of progress on immigration reform, that may not be enough to fix the president's plummeting poll numbers among Hispanic voters.