World War 2: The Complete History describes Poland as an aggressive, military dominated state that wanted to punch above its own weight. Is this correct?

Poland was quite aggressive militarily in the period immediately after WWI as it fought to re-establish itself as a nation and expand back as much as it could to its historic borders before the partition of Poland.

In 1918, the Greater Poland Uprising broke out and lasted until mid 1919, when the Treaty of Versailles recreated the nation of Poland.

In 1919, Poland was also fighting the Poland Lithuania War, which ended in Poland sponsoring the Republic of Central Lithuania breaking away from Lithuania.

In 1919, Poland was also fighting the Polish Ukranian War against the West Ukranian People's Republic (a break away nation from the Ukranian People's Republic, which was a break away from Soviet Ukraine). The West Ukranian People's republic was defeated and a large portion of its territory incorporated into Poland.

In 1919, Poland was also fighting the Polish Soviet War against Soviet Russia and Soviet Ukraine (the Ukrainian People's Republic were allies with the Poles in this war). The Poles were winning at first, advancing to Kiev. Then the Soviets counter attacked, occupying at one point circa half of Poland and attacking Warsaw. Then the Poles counter attacked and ended the war in 1921 with somewhat more territory than they started with.

In 1922, in a disputed election, Poland absorbed the Republic of Central Lithuania (which they had more or less created as a break-away from Lithuania in the earlier Polish Lithuania War).

So, in the immediate aftermath of WWI, when Poland was recreated, it was quite aggressive and militaristic as it fought in a chaotic environment (the aftermath of German victory on the Eastern front, the now crumbled treaty of Brest Litovsk, the Communist Revolution, the war between the Whites and the Reds, etc.) to recreate a nation with most of the territory Poland had traditionally claimed.

Less than two decades later, by the time of the run up to WWII, Poland was no longer so aggressive (partly because both Soviet Russia and Nazi Germany had become much scarier and more powerful than when they were both shattered and defeated nations at the end of WWI). Although Poland might still be characterized as military dominated, this was more out of fear and defensiveness than aggression by the late 1930s.