You can describe this light novel with one word: a power-trip.
The story is based on what I like to call the pyramid of power-trips. Its only goal is to create as many of them as possible.
Every character has a set place in this hierarchy and on top of it is our main character Ainz.
It goes something like this: a new character is introduced. This new character then goes on to have a power-trip destroying the good (or bad) guys until he is met with a similar fate.
Now repeat this over and over again with different characters and minor variations and you can see how it quickly becomes dull.

Just like in many works with an overpowered main character, the focus shifts away from the MC.
There is almost no character development and ironically the antagonists get most of it.

The MC goes against his traits and does irrational things just to have more power-trips (a.k.a. the Lizardmen arc).

The MC simply starts at the top and stays there.

The main character is described as acting only with his own interests in mind and that is a trait that can really make a character deep.
But does the author really need to fill prologues/epilogues with these words over and over again in order for the reader to get it?

I'd say the world building and the character design itself is good and if you are a fan of power-trips, this light novel is definitely for you.