Hello, i just grazed the beta but took most of the time to analyse only the mechanics. The story i know will be great and there are a lot of content missing.
Stats: Nothing changed too much, no complain. I am not sure if the dexterity influence on attack speed will be much more correct this time on the tooltip.
Skills: I simple disliked this system A LOT. 1 Skill per level is almost a complete jump behind (too great for just a step). The companions "raising" your skill total will completely cripple solo play cause the game will be balanced around it. Please, the old style, with cost increasing based on how high a skill with flag bonuses from class and background is incredible better.
Sugestion: Keep active skills apart from "roleplay" skills, but rollback to PoE1 model... you gaining X active and Y roleplay skillpoints with each level with increasing cost (i really liked the model of "add 1 per level" of POE1, balance the game a lot and somewhat "make sense").
Talents: Anothe imense "jump behind". Talents should be talents, classe abilities should be class abilities. Talents everyone should have access to, class abilities only the class have access, simple and easy. Messing the two just made the game even with the multiclass system a LOT less customizable. You could have a +10 Fortitude wizard in PoE1, now you NEED to be a Monk. Another point, some abilities should scale with power levels, but other should scale with flag level to "keep up" (Transcendent Suffering come to mind, since it is supposed to allow unnardmed combat scale like in game weapons you will eventually find.)
Sugestion: The power level scaling seems about right and multiclass should work, but make multiclass just for class abilities and keep 1 talent every even level. The system in the beta is so shallow that almost removed all my hype for the game. (But it is what beta is for, i hope)
Combat Buff/Debuffs: I liked the idea of some buffs having common names across the classes (Concentration, Focused, so on) and maybe some of them just need to be adjusted to make sense (tenacious giving damage dont seem right), but the overall idea is good and make easier to balance some effects.
Combat mechanics: When i first read about penetration i found it ok, when i noticed EVERY effect has penetration it was a little "meh". Making penetration just "reduce DR by X" would be more effective, and i would like the game to mantain X as a very low number. The idea of abilities having cooldown is great for soloplay, but will require a very hard playtest to balance. As long as the game dont become WoW-like ability spam, its ok.
Thats my feedback for now, like i said i only grazed the beta, but the change in talents/class abilities was one of the greatest letdowns that i had in my gaming life (with complete 33 years next monday), the other aspects i dont find good or bad, just different.