As far as I can tell, the most legit complaint re: Obama is the deportations, which feel politically gratuitous as well as morally repugnant. His FP was imperialist 100% but probably less so than any major party presidential candidate in the past 20 years would have been.
and not just in the general. I'm hard pressed to come up with a primary candidate who attracted any significant support who would have done better. Bernie, maybe? But I feel like his FP is so underdeveloped he would have gotten bossed by the generals (...like Obama.)