Over the years I can't tell you how many times I've seen the "It's only Beta" phrase used as a response to dismiss a variety of complaints about features / gameplay etc in the latest beta builds.
However, as someone who has never actually gotten into a Beta though I have played in some PTR's, my sense from following developments on these forums over the years is that Beta is a more a mere tuning pass / bug fix process and that for the most part (95% plus) of what you get in the first beta build is what you get in the final beta build. And often times even with that limited goal the game goes live with with obvious tuning issues (both class balance and particular fights) despite clear feedback that there are issues.
Most of the "significant" things that get changed or dropped appear to be done before the end of the Alpha (Path of Titans, opening zone quests in WoD) and are "locked in" well before players get to even test it and provide feedback. Jade Forest revamping was an exception to this rule but that was also a much different beta due to the need to let the 1 million annual passers into that Beta.
I guess my question, and point is, for those who do a lot of beta testing is: Beyond the tuning of fights and occasional rejigging of certain talents does the final product, in your opinion, change very much from the first beta build released?