You'll need to form your own opinion, but in my opinion the Treaty of Versailles was essentially unjust and unfair. The treaty placed all blame for the cause of the Great War (World War I) on Germany as the leader of the Central Powers. In reality, as detailed by historian Barbara Tuchman in her Pulitzer Prize winning book, The Guns of August (1962), all the involved nations of Europe contributed to process of creating the war.
The Treaty of Versailles also was not a good peace treaty for the future, because the harsh terms put Germany in a situation that allowed the rise of Hitler and the Nazis, leading to World War II.
The Treaty of Versailles, which came out of the Paris Peace Conference in 1919, was very punitive towards Germany. In addition to the "war guilt" clause of the treaty (forcing Germany to admit responsibility for causing the war), Germany also was forced to pay large reparation payments to the war's victorious nations. The German economy and national pride were deeply wounded. Then the Great Depression hit and made things even worse. (Germany's depression conditions were even worse than those in America.) The bad situation in Germany made it possible for a radical leader like Hitler, making all sorts of bold promises, to win over enough people to rise to power. Hitler promised a return to national greatness and fiercely rebuilt Germany as a military machine. The rise of Hitler and the Nazis brought about World War II in Europe.