You have to read the history of Italy during WW2 to know the reasons behind, instead on relying on some people's opinions that are mostly biased.
Mussolini was a dictator who seized power in a coup that overthrew the legitimate and democratic Italian government long before WW2. So It was obvious that ordinary Italians never liked him. Most Italians were against Mussolini's decision in signing the Tri-Partite Pact, the treaty that formed the Axis Alliance between Germany, Italy and Japan. But with a dictatorship in power, the voice of the people means so little. Had a referendum been held at the time, the vast majority of Italians would surely had voted against Italy's joining the Axis. But there was no such referendum in a dictatorship.
It was Mussolini's commitment to the Axis Alliance that dragged Italy into the war. There was a provision in the Tri-Partite Pact wherein it was stated that in the event any one of the three Axis members would be at war with any other nation, the other two would simultaneously declare war in support of their ally.
Everybody knows that Britain and France declared war on Germany as a result of Germany's invasion of Poland (that triggered WW2). Therefore, this automatically puts Italy as a de-facto participant in the war (in support of Germany as required by the treaty) even though Italy never had any interest of its own on Poland. Later on, Italy would again be dragged in exactly the same way to fight against Russia (as a result of Germany's invasion of Russia).
It is very clear that Italy's participation in the war was not because of its own initiative but was mainly due to the commitment made by Mussolini to support Germany in the war.
This was the reason why the Italian Army fought half-heartedly during WW2. Most Italian soldiers felt that they are fighting for Germany rather than fighting for Italy. Furthermore, Italy would have to face war against Britain, France, Russia, and later on America (nations that in reality never actually posed any threat or adversity towards the Italian nation during its past histories).
It is to be noted that in the latter part of WW2, Mussolini was deposed from power during an uprising. With Mussolini out, General Badoglio, the newly installed commander of the Italian Army then immediately arranged for Italy's surrender to the Western Allies. Soon after the surrender, Italy declared war against Germany. Then in the closing days of WW2, Mussolini and his mistress were executed by Italian partisans and their dead bodies hung upside down in a public square.