So many people complaining about this patch...I haven't really had any issues outside of the egalitarians hating me for settling a world with pre-sentients because they consider pre-sentients to always be enslaved apparently. I guess I've just been lucky?
Some of the issues are broken features that affect everyone, you just haven't been looking in the particular spots to notice them (which is fair enough).
The major problem I have with the game at the moment is that "Governing Ethics Attraction" does nothing, and hasn't done anything since 1.5. This effectively means the main spiritualist bonus does nothing, and a whole bunch of buildings, edicts and the planetary mind control laser all do nothing as well. It also means the entire ethos system is way out of whack with what it should be. This is a huge issue if you care about your pops' ethos at all (or play spiritualist), but I can see why you wouldn't immediately notice it. It's hard to tell in general what's going on with pop ethos, none of it is made very clear to the player.
The other one is the AI crippling itself by terraforming its own planets into forms that are useless to them. This completely destroys any chance for the AI to be competitive, but again it's not immediately noticeable because it takes place in AI empires.
This beta patch seems to have been handled right, but as I've said there are still issues in the game that stop me from playing at all. I really hope the intention is to continue with these bug fixes before moving on to anything else this time.
I'd love to be able to (finally) get back into the game properly, a lot of the improvements sound like they would be great if there was only a decent version of the game to play them on.