Truman at Yalta

What if President Franklin Roosevelt died within a week or two of his fourth term's start and thus Vice President Harry Truman (barely inaugurated as VP a few weeks ago himself) was elevated to the United States Presidency and sent to the Yalta Conference in early February to discuss with Winston Churchill and Josef Stalin the future of Europe and Japan?

Would he take a harder line against the Soviets? Make different demands?
Very little is going to be different. Yalta is way overblown. Domination of Eastern Europe by the Soviets was determined by where the Red Army ended up, and by Yalta it was in control of most of those countries. Stalin have certain promises to FDR that he subsequently ignored. He will do the same with Truman.

US goals remain the same - get Stalin's promise to declare war on Japan. Until the atomic bomb is tested, there is no chance this is not the overriding US objective at Yalta. Truman will rely on the existing foreign policy team and carry out FDR's policies.

Any major differences happens after Yalta. Truman will have several more months to get used to being President, and he will have met Stalin already before Potsdam. He will have an already formed opinion of him and Soviet actions by that conference. There may be a slightly different Potsdam, and Truman may react to Soviet actions more quickly than he did IOTL. But these are only slight variations to OTL. Nothing essential can change in Europe at that point.
Agreed in that it won't effect the outcome of WWII very much. I'm thinking more about the impact on the development of the Cold War immediately after World War II. American-Soviet relations and all that.