I have finished the play. I found it very interesting indeed. I do not fully grasp the reason why Estragon seemed to not remember anything. And why does Vladimir suddenly try to make some sense out of things.
I was very stunned when Vladimir told Estragon that they were exactly at the same place yestrday. Estragon doesn´t know. He forgot. Strange because the tree has leaves. Impossible over night, the day before there were no leaves. Vladimir is confused but then he finds luckys hat which he left there yestrday. Still doesn´t answer my question about the leaves though.
Never mind. I was also very surprised that the end of the play was almost identical to the beginning. This stung me! I still cant get rid of the feeling that Vladimir was about to solve the puzzle but is sworn to doom all the time due to not enough support by Estragon who doesn´t remember anything.

Quote 1:
"Let´s go. Yes, let´s go. (they don´t move)."

This could mean in different words; let´s move on. Again by not moving they prove their lack of "will" to do anything or change anything. (Many people do this and I believe Beckett was trying to point this out.)

Quote 2:
"Nothing to be done" (Estragon)

I do believe that he literally means there is nothing HE can do. Nothing he can do about the situation. Perhaps society.

Quote 3:
"Such is life."

They rather get use to this fact then to actually try to change their meaning of "life".

Quote 4:
"We are all born mad. Some remain so."

Through life we gain knowledge and wisdom. Some do not. They remain the same as at their begining in a way.

Quote 5:
"To-morrow, when I wake, or think I do, what shall I say of to-day?"

This has a meaning that I do not grasp. I put it here just to show once more that they aren´t able to even decide for themselves. Asking such questions...