Hmm, as mentioned once you get to Defoe everything is plain sailing. He was one of the earliest examples of a new clarity in written English. With regard to Shakespeare, as someone put it to me a while ago, we are brought up (in the UK, at least) bi-lingual (in English and Shakespeare). But try reading Jonson's Bartholomew Fair and you might find it a lot more difficult. Also try reading letters written at the beginning of the seventeenth century and although you will recognise all the words, you might find it a lot less easy understanding the intent. This is particularly the case of documents not produced for publication and if you have to work with these, it is a fairly time-consuming process. I have fewer problems with seventeenth-century French.
Use of 'gotten' in a novel immediately indicates to us on this side of the Pond that the the writer is not from these shores and tends to detract when the dialogue is supposed to be set here. It kind of jumps off the page at you.
Currently reading - Emergence of a Nation State by Alan Smith