Everyone agrees, even the Americans that Iran has kept its promise, but urged on by Netanyahu of Israel, Trump ( who has no liking for Obama ), has said that he will no longer honor America's commitment to it. The Europeans have made various attempts, including the recent visits by Pres Macron and Chancellor Merkl, to try and convince Trump to honor the deal.
If Trump goes ahead and take the U S out of the deal, it will have very serious consequences. The Iranian will re-start its nuclear program and develop a nuclear arsenal and the world will see other nations, perhaps Saudi Arabia, Brazil, South Africa , even Japan and South Korea do the same for "Deterrence". The North Koreans will definitely carry on their program and any chance of an agreement will fizzle out.
Europe will try to do an end around and try to convince the Iranians to continue to uphold the agreement. They will promise to continue their trade and relationship with Iran, and this will isolate America. it threaten the Europeans and any others who do not toe the American line but the Europeans will stand tough.
America will lose the hard-earned credibility and respect it regained under Obama. No one will trust their words any future agreements ( Trump has pulled out of the Paris climate accord and from the Asian economic agreement and has threatened to leave NAFTA. Israel will be pleased but it is going to be short-lived as turmoil ramps up in the region ( already Hizbollah has gained electoral strength in Lebanon and militarily in Syria and the Saudis continue their genocidal war in Yemen)
Little good will come from Trump withdrawal from the Nuclear agreement, but there will be much harm and the world will be a more dangerous place..