You make these blanket assertions based on what exactly? Republican Doctrine handouts and their Blogs?
Obama would have been a great President but had the Republican Congress throwing roadblocks in front of him constantly. Blame the disfunctional republicans for wasting 7 years in office because they were more concerned with Politics and his birth certificate than getting on with the business of running the country.
He accomplished:
Health Care - not perfect but again it was a compromise with the Congress.
Handled the Wall Street debacle that made the western world teeter on collapse. Bush Jr was way over his head with that mess and it required a steady hand to pull the US economy out of the shit house. Shame on Obama for not sending the Wall St old boys club to jail after that mess.
Saved the Auto Industry from collapse.
Added 4 million jobs during his Presidency.
Reduced unemployment to 5% the lowest it's been in years during a shitty economy.
Put wage equity into law.
Legalized same sex marriage
Bin Laden - got him and dealt with the body so it did not become a touch stone for Jihadists world wide.
Decreased troop levels in Iraq and made Afghanistan the centre to focus on (which it should have been during Bush Jr administration).
Increased the use of Drones UAVs to take out Al Queda in the Persian Gulf states. Did that bring rise to ISIL? It's debatable but it's a certainty that the fight picked by Bush Jr in Iraq brought all the crazies together in one place to fight the infidels from the coalition.
The thing is very little is ever said about the Republicans, their Tea Party and their Negative Effect upon the USA. It's just easier for people to turn around and blame Obama.
IMHO Obama and Bill Clinton were the best Presidents to lead since JFK.
Who did the US have as President since LBJ?
Nixon
Carter
Reagan
Bush Sr
Clinton
Bush Jr
Obama
Try and convince me of any of those Repubilcan Presidents shining more prominently than Clinton or Obama? Ironically, I read recently that Nixon is considered a good President because he ended the Vietnam War and established trade relations with China. Reagan could read a TelePrompter and it's debatable that Bush Jr could actually read. Reagan was present during the collapse of the Berlin Wall and the former Soviet Union but did not do anything instrumental to assist in their downfall. They were already doing that all on their own.
Think about it. The USA would never have had Obama unless their Supreme Court had not appointed Bush Jr in the biggest fraud ever in US history.
Carry on.