Here's an article from an online research journal which is a great resource for all things American Revolution, it has lots of articles about various shows and movies.
Also this blog has some great, detailed posts on the show's accuracy.
The show is based on this book. So a lot of it is quite accurate. Most of the love stories and some other drama details are not accurate or filled in with conjecture. Some dates and locations are fudged to smooth out the storyline. Some characters, like Abigail, are created out of combinations of real people in history.
Can we please make a sticky or something for this question?