Okay, I guess I'll share some thoughts on latest rework of Diablo 4 systems, given I have some time in already (lvl 100 Druid, Hagrid and level 89, Sorceress, Dynaheir)
The game feels better overall. You find more items, with less affixes on it, but those affixes are more powerful and more generalized. It helps with the pacing, comparing items you found and so on. Rares and Legendaries items you found can by upgraded by tempering them at blacksmith - this is a way you are aiming for more build-specific affixes. Additional damage to companions, cooldown reduciton on specific skills, increased area of effects, chance to proc effect on hit etc. In contrast to the previous system, you are adding those specific things and you have more control over what specific affixes you can have on items, as opposed to finding a lot of sh*t, taking a ton of time to compare the the items and having hard time to decide what you'd want from it. All in all, it is positive change for the game.
Tempered items and Uniques can be strengthened by masterworking. It is an endgame system that replaces the previous upgrading system. It is expensive, and to get the materials for it you need to partake in an endgame activity like the Pit. The Pit can be very fun, but it also suffers from issues I'll mention later.
Example of an item that was tempered and then masterworked. Anvil symbolizes affixes that were added in tempering, blue numbers received an additional +25% boost courtesy of milestone level of masterworking:
Helltides were fun in the new rework in PTR and they are still fun now. They are available even in lower difficulty settings if the campaign is finished. There is generally more things to do, they are more rewarding and you can even summon a boss, defeating which usually results in some sweet loot. As you kill demons and open special chests, your "threat meter" rises and so you'll be ambushed by stronger waves of demons, culminating in fighting against a hell-possessed version of one of the player characters.
Unique items: let's start from the good. They can also be masterworked. When compared to tempered items, there are plenty that are still viable, and in some cases, crucial for the builds. And Shako will always be good. However, when it comes to weapons, things are starting to get ugly. For example, take a look at the Unique item and what Dynaheir is using:
Now, the Oculus has a really nice flavour to it: a massive skill bonus to Teleport means greatly reduced cooldown and increased nova damage (yes, in D4 teleport casts a small nova on landing). With skill points invested in improving the nova damage, in theory, it encourages using teleport often for devastating results, right? And not to mention the Teleport Enchantment (meaning instead of standard dodge, you have additional "charges" on teleport on cooldown). It has also +29% damage. Cool right?
Well, no, actually. Look at what you are losing. Lots of crit damage (or any other +damage affix you can have instead), +43% damage from tempering and proc of flat damage from lucky hit chance. Dynaheir is also losing her attack speed which is helpful for procing effect she is relying on. When testing using these two different weapons, I find that Oculus's cool flavour and resulting combat style is simply much inferior. And Dynaheir isn't that powerful, she struggles in some endgame activities for now, like the Pit.
I had similar feelings for other weapon uniques. Sorry, but the sheer damage gain you can have from tempering is just usually much better than cool stuff Unique weapons have. Which is quite a shame.
Rare and magic items are useless now, same for vendors (since they don't sell unique and legendaries). The developers said something about giving those items purpose in further updates, but I don't know what this can be. Maybe they'll be bases for runewords or something?
Now, my biggest peeve with the game right now is the difficulty. It starts as piss easy and it mostly stays that way from World Tier I to World Tier III. The result is often that you can comfortably get to higher World Tiers while under-leveled. And at the start of World Tier IV, this is also the case. In fact, for most of the content, this is the case. However, as you progress through the levels of the Pit or Nightmare Dungeons, something happens. You see, the difficulty rises at a steady pace, that's not a big deal. It's just a bit harder, and a bit harder. You still doing fine, you're going through the dungeon just fine, and then you die instantly for a reason you cannot comprehend. I paint it with a broad stroke, but this is essentially the problem: one moment you're doing fine, the other you are put in a situation in which you just die and you don't know why or what you could have done better. Basically, in the same area you are clearing semi-comfortably, there are sudden and unpredictable difficulty spikes and that's just not fun. Even though the game doesn't punish death as severely as D2 did, I still would rather die in D2, where at least I know what I did wrong or what series of unfortunate events had lead to it.
Also when you know what you are doing and unless you are in deeper Nightmare Dungeons, the Butcher is now the B*tcher. He's not scary anymore. In short, I think the difficulty needs to be adjusted and I think it should be done in a thoughtful manner.
And due to the sudden difficulty spikes resulting in nearly instant deaths, I don't want to play hardcore in D4 as of right now. Maybe in the future, but definitely not right now. I don't recommend playing hardcore unless you want to get angry.
The Pit has the same difficulty problem as Nightmare Dungeons, but the Pit has a time limit to clear and you are time penalized after each death. This would work really fine, if it wasn't for above-mentioned difficulty issue. Lower levels of the Pit are however really fun, since the sudden deaths aren't the case there.
What can I say is that the game certainly went into right direction, but there's still work to be done. Can you have fun in this game? Yes. Can it also be furstrating at times? Also yes.