I wasn't saying that you should be satisfied with just the release notes, I was pointing out that you were overstating the difficulty in finding an overview of the changes that went into Python 3.
There are lots of other changes since then, but most of them are additions (that don't directly impact old code) or to libraries or whatever.
A lot of the PEPs are way too verbose for a quick bite. PEP are great for a weekend read, but for a quick summary, OP does a better job.