Chapter 1 & 2 Feedback

Bits and pieces as I come across them.
Chapter 1: More is coming, I wager.
Chapter 2: New Character Classes. "The Player’s Companion doubles your choices, with twelve new character classes to expand your Adventurer Conqueror King System campaigns: barbarian, dwarven machinist, dwarven spelunker, elven enchanter, elven ranger, mystic, and shaman. " Presumably there will eventually be twelve, and they’ll be listed there, but that’s not currently the case. Priestess is currently missing from the list.
Barbarian: Yeah, that’s awesome. Hits the important points and leaves the rest to proficiencies. Nice.
Dwarven Machinist: Steamy. I get the impression that it will start out weak compared to other classes since automatons won’t be affordable for a while. I could see a short list of common automaton abilities being handy. Automatons that require an operator look rather a lot like magic items; could a dwarven machinist design, say, powered boots of leaping? Strength-amplifying suits of armor? Death ray helmets? Non-mobile automatons could fill the role of fancy dungeon tricks & traps - flame vents, crushing ceilings, elevators, rotating rooms, etc. I wonder if calling that out and providing an example or two might be useful. Bonus point for including “dweomercraft,” one of my favorite words.
Dwarven Spelunker: “Beyond the confined vaults where the dwarves live and work run labyrinthine caverns and winding tunnels stretching hundreds and perhaps thousands of miles under the earth.” Great detail of the implied setting with lots of potential consequences. “… his experience and hardiness reassures those who follow him into the underdark.” Are you sure you want to use that word, Underdark™? Hireling bonus in dungeons is a nice touch. Even though the design reason makes sense, leather armor just seems un-dwarven to me.
Elven Enchanter: With the long list of innate abilities, this beats the mage hands down (until levels 13/14, and that’s debatable) in function and survivability for a ~13% experience penalty and tougher qualifications for prime requisite bonus. Other demi-human classes have some kind of trade-off versus the base class (e.g., dwarven vaultguards not having two-handed weapons, elven ranger d6 HD), but this looks like the entire mage package plus a lot more. Am I missing something? Or is this the reward class for rolling a high charisma mage? The attack & save table still has the level 13/14 line, which it won’t need. I don’t see anything about automatically learning spells from a master until 9th level.
Elven Ranger: …yep, that pretty much sums it up. Damn elves.
Mystic: Nicely done. I like the Jedi/Dune overtones and the WIS/CHA interplay. That looks like it’d be a lot of fun to play.
Priestess: Fills the divine mage niche quite nicely. With some minor tweaks - spell list, flavor, a couple of proficiency swaps - this is also a great necromancer.
Shaman: Awesome. Creating magical constructs seems a little out of place, makes me think of the Enchanted Tiki Room.

Elven enchanter is built with the class building rules.
Three points in mage
one point in thief (sacrificing the three abilities for the enchanter ones).
Then one point into elf which stacks with mage and gives the level limits.

Dwarven Machinist: Steamy. I get the impression that it will start out weak compared to other classes since automatons won’t be affordable for a while. I could see a short list of common automaton abilities being handy. Automatons that require an operator look rather a lot like magic items; could a dwarven machinist design, say, powered boots of leaping? Strength-amplifying suits of armor? Death ray helmets? Non-mobile automatons could fill the role of fancy dungeon tricks & traps - flame vents, crushing ceilings, elevators, rotating rooms, etc. I wonder if calling that out and providing an example or two might be useful. Bonus point for including “dweomercraft,” one of my favorite words.
APM: Automatons that require an operator are indeed suspiciously similar to magic items. It is (purposefully) left to the Judge’s discretion as to what special abilities are permitted. A Judge who wants to have more of a steampunk-flavored game can be more gonzo.
Dwarven Spelunker: “Beyond the confined vaults where the dwarves live and work run labyrinthine caverns and winding tunnels stretching hundreds and perhaps thousands of miles under the earth.” Great detail of the implied setting with lots of potential consequences. “… his experience and hardiness reassures those who follow him into the underdark.” Are you sure you want to use that word, Underdark™? Hireling bonus in dungeons is a nice touch. Even though the design reason makes sense, leather armor just seems un-dwarven to me.
APM: I hadn’t realized underdark was trademarked. That’s too bad, it’s a cool word.
Elven Enchanter: With the long list of innate abilities, this beats the mage hands down (until levels 13/14, and that’s debatable) in function and survivability for a ~13% experience penalty and tougher qualifications for prime requisite bonus. Other demi-human classes have some kind of trade-off versus the base class (e.g., dwarven vaultguards not having two-handed weapons, elven ranger d6 HD), but this looks like the entire mage package plus a lot more. Am I missing something? Or is this the reward class for rolling a high charisma mage? The attack & save table still has the level 13/14 line, which it won’t need. I don’t see anything about automatically learning spells from a master until 9th level.
APM: Tywyll is correct that the elven enchanter is built with the class building rules. That said, the elven enchanter does not have access to the Battle Magic, Black Lore of Zahar, and Elementalism proficiencies, which are the three of the best proficiencies available to adventuring mages.
Certainly, if you want a caster that excels in charms and illusions, and you qualify, there’s no reason not to be an elven enchanter over mage. On the other hand, given the very limited number of spells in an arcane caster’s repertoire, if you don’t intend to be charmer/illusionist, choosing to be an elven enchanter is not worthwhile. A necromancer, battle-wizard, or elementalist should certainly choose to be a mage instead.
All arcane spellcasters learn spells from a master until 9th level, so I don’t think(?) it’s necessary to say that.

A quick search suggests that underdark may only be trademarked in “Battle for the Underdark” rather than itself alone. Still, it carries a certain amount of baggage. It’s a wee thing that’s unlikely to be important, but I thought I’d point it out.
This missing mage proficiencies for the enchanter is the trade-off I missed. Makes total sense.
If it specifically mentions somewhere that all arcane spellcasters learn spells from a master - rather than just in the mage description - then it’s not necessary, no. It’s probably lurking in the class building rules I haven’t reached yet.