I found this Time's article about MacArthur, are the criticisms about him fair to make with respect to his predicament during the events and the time preceding it? And is everything on paragraph 4 and beyond accurate?
It's mostly accurate. It's also partly fair, but not entirely. First, many good and even superb generals make mistakes. Pointing out a few mistakes by a general is not enough to really say "over-rated". Some of the things discussed in the article merit more discussion. Second, I'll begin with WWII (and ignore the Bonus Marchers).
The defence of the Philippines was mismanaged. Not mentioned in the article is the basic plan for defence against a Japanese invasion. The original plan for the defence of Luzon had been based on the defence of Bataan and Corregidor, since the forces available were insufficient to try to hold all of Luzon. What MacArthur had been working on for some time had been to build up the Philippine defence forces, and perhaps he was sufficiently encouraged by his progress to expand his plans to defend Luzon, and shifted to a plan to defend the whole island. However, the Philippine forces, while larger, were immature - poorly trained and equipped - and were far from capable of what MacArthur was asking (MacArthur's plans might have also underestimated the Japanese). In the event, this seriously hampered the defence of the Philippines, since supplies were spread around Luzon, instead of concentrated in Bataan and Corregidor where they might have enabled a longer (but quite possibly still unsuccessful) defence.
As for aircraft destroyed on the ground the day after Pearl Harbor, Hap Arnold had ordered the Far East Air Force (FEAF) make sure that their aircraft were not destroyed on the ground, earlier in the morning. In respond, FEAF had put many fighter and all bombers into the air, between 8am and 8:30; these aircraft had landed by 11am, and the bombers were to prepare for a raid on Formosa (Taiwan). Then they were mostly caught by surprise by the incoming Japanese raids from Formosa (which had been planned for earlier, but had been delayed by bad weather). Clearly, FEAF had poor luck with the timing of the Japanese attack, and MacArthur is not entirely to blame. To what extent was MacArthur to blame? There was confusion and miscommunication which meant that early warning of the Japanese raids was limited, despite their detection by radar. This kind of thing is difficult to get right on the first day of a war! It would also have been wise to have better dispersed the aircraft after they landed in the late morning, to make them less vulnerable. Dispersal of aircraft was not the kind of micromanagement that MacArthur should have been doing that day - it should have been SOP when at war. More wisely, MacArthur had moved quite a number of aircraft, including about half of the B-17s, to bases in Mindanao, out of range of raids from Formosa. Overall, FEAF preparedness was poor, and command and control was poor, for which MacArthur bears some responsibility. However, he had taken some sensible precautions, and suffered from some poor luck.
Finally, for the defence of the Philippines, MacArthur's escape from Corregidor has the perfect justification of orders of above. While MacArthur did not always follow orders, it is difficult to fault him for an occasion when he did.
While the article doesn't mention MacArthur's defence of New Guinea, it is worth commenting on. MacArthur's intelligence was poor - he was willing to let his preconceptions take precedence over intelligence, and his intelligence service was aware of this and perhaps excessively filtered incoming intelligence. Thus, the Japanese attempt to take Port Moresby by land, attacking along the Kokoda Track, came by surprise, and the Japanese forces involved were underestimated. The Kokoda campaign has made MacArthur a far less popular figure in Australia than he otherwise would have been: as green Australian forces were pushed back along the track by better-equipped and numerically-superior Japanese forces, MacArthur was quick to blame the Australians and their fighting ability, rather than his own poor defensive plans (and probably still believed his intelligence which seriously underestimated the Japanese attack). The Kokoda campaign was largely decided by logistics, as the Japanese supply lines failed as the Japanese advanced almost to Port Moresby, and now numerically-superior Australian forces, with air support, were able to push the Japanese back. MacArthur took full credit for the victory - the initial reverse was the fault of the Australians (and not MacArthur), and the eventual victory was due to MacArthur (and not the Australians). The comments in the article on MacArthur's attitude to publicity are accurate.
There is also an Australian perception that MacArthur wasted Australian lives to gain victory in unnecessary battles in New Guinea. Certainly, MacArthur claimed credit for the victories, but (a) it can be difficult to defeat an enemy without battles, (b) US forces were heavily involved, too (and often suffered badly, e.g., at Buna-Gona), and (c) many bloody potential battles were avoided (e.g., Rabaul was isolated rather than invaded). Indeed, some of the bloody battles were the responsibility of the Australian government (e.g., much of the fighting on Bougainville).
Peleliu is not just MacArthur's fault. One of the attractions of Peleliu was that it could be used as a base for an attack on Okinawa as well as the Philippines - it fit into both MacArthur's South Pacific-Philippines drive and the Navy's Central Pacific-Okinawa-Formosa drive (from which Formosa was later dropped). In the event, Ulithi Atoll was taken unopposed (having been abandoned by the Japanese) about a week after the landings on Peleliu, and was developed into a large naval and air base, while the fighting on Peleliu continued for another two months. It was Ulithi that would be the base for the attack on Okinawa.
As for Korea, Incheon is often hailed as a great and stunning victory, MacArthur's masterpiece. The Incheon landings themselves went very well. The problem was what came next. There were two choices:(a) take Seoul, or (b) bypass Seoul. The latter would have left a large, and possibly soon-reinforced North Korean force directly to the north of UN lines, and was probably thoroughly unacceptable to Syngman Rhee, the president of South Korea. The protracted fighting for Seoul meant that the Incheon landing didn't achieve one of it major strategic objectives - to cut off North Korean forces in the south. MacArthur's response to this, if properly foreseen and willing to leave Seoul alone, probably should have been to land elsewhere, rather than to take Incheon and bypass Seoul.
MacArthur's greatest failings in Korea were still to come: (a) not following orders (taking the war into the north, and then to the Yalu, seeking retrospective approval rather than prior authorisation, and his insubordination which led to his sacking); (b) a catastrophic intelligence failure concerning Chinese intentions and capabilities regarding the Chinese entry into the war; and (c) failing to stop the Chinese advance (a failure of command and control, and also of intelligence). That the Chinese advance could be stopped, without enormous reinforcement or atomic bombing, was demonstrated by Matthew Ridgway, first as commander of the US 8th Army following Walton Walker's death in a road accident, and then as MacArthur's replacement as UN forces commander.
MacArthur had failings, and made mistakes, as did/do many generals. Was he a great general? While there was mismanagement of the defence of the Philippines, after the destruction of the US battle fleet at Pearl Harbor, there was no realistic chance to defend the Philippines (e.g., by holding Bataan and Corregidor until the US Navy could arrive and defeat the Japanese Navy). His defence of New Guinea and drive to the Philippines was certainly competent at least. The fighting for Seoul might have been a mistake (and therefore the landing at Incheon, despite its success), but insubordination aside, his performance in Korea was at least competent, until the disaster of the Chinese entry. From the Chinese entry into the Korean War onward, MacArthur's failure is a major black mark on his record.
There are no universal criteria for "great general", so any assessment of MacArthur's greatness/non-greatness must be subjective. MacArthur often polarises opinions. Many do regard him as a great general, and he is a national hero in Korea. He also had many enemies, perhaps the most vocal being Admiral Ernest King (who was a vocal enemy of others as well). History and public opinion have has not treated him kindly in the US and Australia, but any description of him as "the worst general in American history":
ignores many very bad generals indeed (often little known, due to short careers). For a more balanced discussion of MacArthur, and the ego-related failings that many often-dscribed-as-great generals have, see: