Impressively, the article includes links to high-resolution PDFs of the entire manuscript.
Apparently Dickens was unimpressed with Hamlet and said so on page one of the manuscript, and then thought better of it and scratched it out. But it's still readable and it says:
Perhaps you think that Hamlet's intellects were strong. I doubt it. If you could have such a son tomorrow, depend upon it, you would find him a poser. He would be a most impracticable fellow to deal with, and however creditable he might be to the family, after his decease, he would prove a special incumbrance in his lifetime, trust me.
Ooh, naughty Dickens.