*It has put the caliphate project back on track after almost a century of Muslim humiliation
*It has made sharia (at least its version) the basis of its social order
*It has (correctly) targeted Saudi Arabia as the font of corruption and decadence, the Muslim world's 'enemy at home'
*It is set to become the only 'state' to back its currency with gold coinage. ISIS says the new currency will take the group out of "the oppressors' money system", and return control over the money supply from bankers to the state.
IS is ghoulishly depicted in western media as blood-thirsty murderers reveling in violence, mad nihilists intent on destruction. To put things in perspective, the US is killing dozens if not hundreds of Muslims (quite a number of them babies) every day, all of them innocent of anything beyond defending their lands and homes. Remember the fairytale of Saddam Hussein killing babies on the eve of the 1991 Gulf War? All revolutions spill blood of those who profess to be hostile to the new order, and IS is no exception. In Cuba, between 500 and 2,000 enemies of the state were executed following the 1959 revolution.
The Middle East is in revolutionary upheaval, and has been for a century now. Just as the Russian revolution of 1917 was the logical conclusion of upheavals against imperialism in yesteryear, so Islamic revolutions are the logical consequence of imperialism today. The Iranian revolution of 1979 set the stage, and actions of the US in the past two decades (since the first invasion of Iraq in 1991) have ensured that this upheaval will continue and have an Islamic nature.
The end of communism came by the imperialists wearing down the secular communists through war and subversion until the system was sufficiently weakened, allowing internal dissent to overthrow it. Is this really the plan today? Unending torment and slaughter inflicted by the West on the Middle East? Keep in mind, Islamic resistance is grounded in a much more convincing way than was communism, and will not be defeated so easily.
The major stumbling block in coming to terms with IS is its insistence that while its ultimate goal is to dismantle Israel, the first step in this process is for Muslims to rid the Muslim world of its fifth column. That flies in the face of 70 years of official resistance by Arab governments (put in place by Britain-US) and the Palestinian support movement (dominated by soft Zionists, urging acceptance of Israel as a Jewish state). The Arab governments are corrupt and venal, and benefit unjustifiably by hiding behind the Palestinians. The Palestinian support movement is timid and ineffectual. Genuine supporters of the Palestinians realize this and realize that Saudi-led 'resistance' to Israel will never lead to a liberated Middle East.
So IS has a point, and we can't just dismiss its strategy out of hand. CIA agent Mortem Storm revealed that Saudi officials proposed a deal to Al-Qaeda in the Arab Peninsula leader Nasir al-Wuhayshi in 2011: "They would pardon Wuhayshi and donate weapons and money if they stopped fighting the Saudis and the Americans and focused instead on fighting Shia rebels in northern Yemen." Simply put, the Saudis are Islam's fifth column, and IS is the only group willing to say this openly. IS leader Abu Bakr al-Baghdadi renewed his call for attacks against the rulers of Saudi Arabia in November. "We announce to you the expansion of the Islamic State to new countries, to the countries of the Haramayn [Saudi Arabia], Yemen, Egypt, Libya, Algeria. O soldiers of the Islamic State ... erupt volcanoes of jihad everywhere. Light the earth with fire against all dictators."
As for IS's reported atrocities, given IS's commitment to sharia and the Quran, those Christians and Shia caught in the (Sunni) IS order--if they value their lives and want to remain in their homes--must organize and present themselves to IS leaders as loyal citizens, opposed to IS's enemies--the West, Israel and Saudi Arabia. Sharia makes allowance for the protection of non-Muslims, who must pay a protection tax (jizya). That will end the sectarianism.
At present, these dissidents are sitting ducks, and the crocodile tears of western leaders and the media are making things worse for them. This cynical use of dissidents has long been ammunition in the western arsenal to confront imperialism's enemies, as the Soviet Union experienced. They are custom-made martyrs for western media--and quickly discarded when the West's armies and carpetbaggers are welcomed as liberators.
Given the nightmare that US invasions have resulted in during the past quarter century, and that Israeli invasions have resulted in during the past 70 years, the rough edges of the revolutionaries will have to be tolerated by fretful liberals as the lesser of two evils--women and minorities are suffering horrendously under US 'protection' now. Over time, the hard edges of the revolution will be worn down and women and minorities will be better accommodated, as even Saudi Arabia crudely shows.