Pros:
One of the main advantages of monotheism is that if there is only one God so there is only one correct way to act
Cons:
A monotheist has to reconcile all the bad things in the human condition with a god worthy of worship, while polytheists have the advantage of dividing good and evil into different camps of gods.
Lacks of any intermediary or intervening aspects or factors between yourself and god
Lack of options so to say A polytheist has a variety of gods for different emotional needs, aesthetic tastes and social gatherings. A monotheist has just one to cover all bases and so will often end up making this deity supreme or all encompassing