Throughout history, empires have come into being and then come to pass. They grow by acquiring or conquering neighboring territories, and once large enough, can stabilize the politics of a region enough so that the positive effects of peace and prosperity through trade can occur. Unfortunately, like all human institutions, they can become corrupt over time as well. It appears that they expand or die, and if expanded enough, die anyway by breaking apart (like Rome or Alexander the Great's empire.) Their creation and dissolution always involve the negative of warfare; even when stable, they tend to suppress any dissidence within its borders to maintain that stability. The ancient ones you have listed unfortunately share these similarities with the modern ones of our time.
I'm not quite clear on one aspect of this question: positive and negative effects FOR WHOM? Are you asking about the effects on the people who rule the empire or on the ruled? I'll answer this with a focus on the ruled.
For people who fall under an empire, there are positives and negatives. The most usual potential positives are 1) better economic opportunities and 2) more security.
Empires allow for better economic opportunities (especially in the old days) because they allowed for trade between various areas. Trade between countries could be banned or be too dangerous, but trade within an empire would not be.
Empires can provide better security for many people because they will not be subject to wars going on between countries. This was the idea behind the "Pax Romana" during the Roman Empire. Instead of having lots of countries fighting (and potentially destroying your crops and property) you get peace.
The negatives are that you get ruled and the rulers will care more about what's good for them than what's good for you.