what does it mean?
Since then, all of us spiders have had to work the same trick. It's not a bad pitch, on the whole.

what does "It's not a bad pitch, on the whole" mean?

Thank you in advance!More context:
I don't know how the first spider in the early days of the world happened to think up thisn fancy idea of spinning a web, but she did, and it was clever of her,too. And since then, all of us spiders have had to work the same trick. It's not a bad pitch, on the whole.

The above is from Charlotte's Web by E.B.White.

And a spider named Charlotte makes the talk.

Question

what does it mean?
Since then, all of us spiders have had to work the same trick. It's not a bad pitch, on the whole.

what does "It's not a bad pitch, on the whole" mean?

Thank you in advance!More context:
I don't know how the first spider in the early days of the world happened to think up thisn fancy idea of spinning a web, but she did, and it was clever of her,too. And since then, all of us spiders have had to work the same trick. It's not a bad pitch, on the whole. 

The above is from Charlotte's Web by E.B.White.

And a spider named Charlotte makes the talk.

Answer

You definitely need more context to reliably answer this question. 
We would need to know what "us spiders" was referring to at the least.

The word pitch can have many meanings.
Examples
. level playing fields (spiders may be on a level field).
. to throw
. to erect a tent
. to set at a particular angle.
. to rock back and forward by a ship.
. a salesperson's talk.

Just guessing what "a bad pitch" means here,  one clue would be "the same trick".
I think that this pitch here is some type of sales talk, but more context would help.

Answer

It seems like, "it's not a bad pitch, on the whole" means that he is not unhappy with the outcome or situation.

Answer

A level or degree, as of intensity: worked at a feverish pitch to meet the deadline.

Actually I need more context.

Answer

I think that the closest meaning would be.
 pitch - a place where a street performer of trader is stationed.

so as 할아버지 / 祖父 says, Charlotte is happy with the pitch which in this case refers to spiders sitting on a web.

Willow : a note: this is not a clear cut outcome. It is one of things a good author does, create word images that could be understood in many ways. As a result, different people can see different things in the same work.