My startup, Casetext (YC S13), has the full text of the SAFE annotated by lawyers, investors, and founders: https://casetext.com/contract/simple-agreement-for-future-eq...

This looks like a pretty good place to start:

http://ycombinator.com/safe/

Discussion of the original announcement: https://news.ycombinator.com/item?id=6862461 (487 points, 33 days ago, 117 comments). In particular read the first comment, from user grellas. (He is a lawyer.)