Barring bugs and server issues two things that - design wise - are unambiguous downgrades from Horizons is the ship storage/transfer menus and outfitting.
For ship transfer, you can no longer check what modules you have on stored ships.
Given some people have taken to using ships to store modules to get around the 120 module limit on storage... Well, I also complain because I wanna check what's on a ship before I decide if I want to transfer it to my location.
For outfitting, much the same, you can't see what engineering is on a module unless you outfit it to your ship, leave outfitting and check it. And you can't check the engineering details at all on stored modules. They've also obfuscated how any given module will change your ships stats and performance if outfitted.
They've also added layers of mess to actually mounting stored modules. And I've been holding off checking out exactly how because they messed with the buy/sell system so that if you're just messing around you may accidentally sell your modules rather than put them in storage.
For now, Horizons still has the old system, and people have taken to swapping to Odyssey for outfitting - which is a sign of a quality user interface upgrade to be sure.
About the only good thing about these particular changes is the shipyard - now available at most stations, and every shipyard lets you view (though not purchase) every ship.
But yeah, overall, the interface won't tell you shit about the stuff you actually have.
The new engineer grind does have one thing going for it, and that is, at first glance it looks like one slot, one upgrade, so it looks less like gradually improve and more customize and improve in discrete stages.
But as mentioned, it requires crazy amounts of grind to actually get to that point so I've not actually checked if that's the case. If it is, it means the high price is, at least fixed and predictable, so you can know exactly the cost of engineering to desired spec.
If it isn't, though... Oooh boy.
Progression in the two new ranks is... Well, okayish. Grindy, but it's Elite, it's to be expected.
They took away the percentages for all the progress bars, which is another point of interface obfuscation.
And they've apparently messed up the superpower rank grind (which is why I'm glad I'm done with that for now).
Doing merc work to advance the mercenary rank is fairly rewarding in terms of credits (though not as rewarding as flying, though you'll pay for infantry basic kit in one go - around, so can be a decent investment). Given the on foot gear is more expensive than the cheaper ships...
Exobiology is a lot more legwork, and less credits, but you get more progress for each individual point of work (thougj the effort is somewhat variable), and combine it with the other exploration, it's a fairly risk free way of getting by and seeing the sights - the new graphics are great where they've put the effort in (just too bad they're also terrible where they haven't).
All told, it's definitely early access. I won't deign to call it a beta, as far as I'm concerned, this is still in alpha. Maybe we'll hit beta before console release.