Actually, no, not really. There was a list of changes to the Core but it was before 3.0 take 1 was scrapped (the one that made it incompatible with 2.0) and the current version does not have a proper list of differences. The two key items are LDP and OAuth2+OIDC support that you should be concerned about, the rest are minor in terms of the dev effort. There is an opinion that https://github.com/oslc-op/oslc-specs/milestone/14 and https://github.com/oslc-op/oslc-specs/milestone/12 with a list of tickets closed are enough but I disagree with that personally.
Regarding the CM, RM, and QM specs there should be nothing new except for the fact that shapes were not published officially before and there some minor problems in the vocabs that were fixed. Also, conformance clauses were added but I see them as pretty useless because they can lose numbering across document releases.
I would really like to have a proper list of changes in the release notes so maybe we should work on it. It will be also helpful if someone like you who knows OSLC but was not involved in the drafting of the new round of specs helps us with the fresh pair of eyes helps us.
As a matter of fact, may I invite you and @jad @DavidJHoney @ndjc to contribute to the https://hackmd.io/@driib/oslc3-release-notes-v1/edit document (you need to sign in through github to be allowed to edit, no extra permissions needed)? I started to jot down a few things that came to my mind, please feel free to add items or add comments. I would like us to publish it later as a Project Note just as Config Primer (we are using a simple Markdown->ReSpec process here so the work on the markdown draft will not be in vain).