A few things from beta, that I have no idea if got fixed.
1. the willpower/rage mechanic will drive people away. I never learned how to use it in any meaningful way. Just kept making mages, with staves to regen willpower, and taking every passive/gear piece to increase willpower, to the point I could cast spells nonstop, and use willpower flasks to refill.
2. Caster gear sucked shit. Anyone can use any armor at any time. there isn't even str/wisdom/etc requirements like poe. Force shield with the beta passives was total garbage. No reason to go it, when you can stack toughness to get health, and damage. and heavy armors giving health, resists. (Bruiser armor iirc was the ideal caster gear. probably for rogues too)
3. dots and damage ailments were total garbage. They didn't scale at all. like, "deals 100 damage per second" and you have +500% damage, it still only did 100 damage per second, while your direct hits were going from 100/hit to 5000/hit. This seemed just broken. a large reason no one was playing mages, and everyone was warriors in beta.
the ailment system itself has other restrictions. if you can apply 3 ailments in one hit for example, weakness, a fire dot, and vulnerability. only one will apply per hit naturally. (iirc it cycles.) Something to consider when equipping items, etc. There are passives that increase this.
4. there is a ton of flat damage added via gems, and on gear. This makes faster cast/attack pretty valuable. There were a few faster attack auto attack builds in beta, using uniques that gave like +200 flat damage.
5. PoE is the only game to get attributes right. this game is no real exception. This game has a system were you can invest in 4 attributes. the attribute with the highest investment gives like 50% of its value as increased damage%, the second most invested gives 40%, the 3rd 30%, and forth 20%. (like rykkher, these numbers are estimated, I dont remember the specific)
toughness gives health and force shield. so, is pretty obvious, stacking toughness will give you the most DAMAGE AND LIFE. Ferocity is spell and attack crit. so, is pure glass cannon, and likely the best secondary stat. Depending on how difficult the game ends up being, possibly the primary stat, with toughness just stacked until you mean the proper survival value. Agility is just attack/cast speed, so secondary or even primary in that rare added damage build. Wisdom was Ailment application chance, which as stated were total garbage, so no one took.
in beta there were no "x happens when you crit" like poe iirc, so no special reason to stack crit like that.
Edit:I just double checked beta vs rhykker.
Attributes did change. for the worse?
Beta attributes. Ferocity was health regen and crit chance.
toughness was health and resists.
agil was dodge, and attack/cast speed.
wisdom was ailment resist, and application chance.
so, each node had one "defensive" purpose before. even if toughness was still the obvious choice. they removed those defensive elements, and did change toughness a bit. the removal of resists is big. life AND resist made it a god stat for sure. but, removing the defenses from the others, still keeps it a god stat with just health... The force shield element may go a long way into making force shield or hybrid builds viable. dunno. still getting life there, so why would I bother?