Why was Neville Chamberlain criticized?

Neville Chamberlain was criticized primarily for his policy of appeasement toward Adolf Hitler and Nazi Germany in the late 1930s, which is seen as failing to prevent World War II. Chamberlain was British Prime Minister from 1937 to 1940 and pursued appeasement, believing that by granting concessions to Hitler, he could avoid war. He is most criticized for Munich Agreement in September 1938, where he and French Prime Minister Daladier agreed to let Germany annex Sudetenland region of Czechoslovakia in exchange for Hitler's promise of peace, returning to Britain declaring peace for our time. Critics say this emboldened Hitler, who then invaded rest of Czechoslovakia and Poland, starting WWII. Chamberlain underestimated Hitler's ambitions and trusted his promises. He was also criticized for slow rearmament of Britain and for not allying with Soviet Union. After war began, his war leadership was seen as weak, leading to resignation in May 1940 after Norway failure, replaced by Winston Churchill. Historians now offer more nuanced view, noting Chamberlain faced public anti-war sentiment and needed time to rearm, but at time and since, he is criticized as naive and as symbol of failed appeasement, with phrase Munich used to mean foolish concession to aggressor.