Here’s my view on what has come out so far:
Races: These are pretty good, but there’s absolutely nothing here to justify the lower stat gains from the PHB races. If anything the PHB races tend to have more racial traits than these anyway. Unless there’s a PHB errata on the horizon we’re unaware of the reduced stat boosts are glaring and unacceptable. Thankfully, they are easily repaired.
Changeling: Beef up the Charisma boost to +2. I like the idea that Changelings have to have seen a humanoid in order to transform into it; they aren’t all master sculptors, sketch artists, etc. Still, I think within reason I’d allow the Changeling to make some easy cosmetic changes to the “template” they choose. I’ve seen Tom Cruise enough times to turn into him, but once Tom Cruise it’s an easy thing to change my hair pink, or put on 20 pounds. These are all reasonable abilities that any reasonable DM should allow. Keep in mind that this is really the Changeling’s only shtick, and it’s already hampered by not being able to transform clothing or equipment, and also by living in a world where everyone knows Changelings exist, so the smallest errors are more likely to be scrutinized. I would have expected a bonus (such as advantage) on saves against mind-reading also, but its absence in a world without psionics isn’t too glaring.
Shifter: These stat boosts are a bit of a mess. What I’d do is fold the Wildhunt subrace into the main race (that is, main race’s stat boost becomes +1 Wis, and all Shifters get the advantage on Wis skills and saves while shifting). Then turn the stat boost from the subrace into +2. Otherwise this is my favorite of the three races presented by far; I was not expecting so many shifter traits and was pleasantly surprised by what we did get. Maybe could eventually build up to 2 shifts per rest at a higher level?
Warforged: Con +2. Otherwise serviceable, if a bit dull. I don’t mind the +1 AC or Warforged wearing armor (or bonding with the armor, as the case may be). They may be living constructs but there’s still an element of magic implied in that construct that makes me really like the idea of Warforged soldiers scavenging the battlefield for bits of armor to replace or improve their own, and I think that fits the lore for the race rather neatly. Would like to see more nods to the Warforged’s resiliency or construction for the purposes of war. Some traits I’d kicked around in my homebrew include gaining bonus hit die when healing on short rests or adding half proficiency to all non-proficient weapons (including unarmed and improvised).
Artificer: Zzzzzz. It’s tough, I know, because the Bard chassis fits a bit better but many of the main class traits and spell list don’t match quite so well as Wizard does, and even then Wizard is missing quite a few iconic Artificer spells, though those are easy enough to add (repair/destroy construct is an easy analogue to cure/cause wounds). You could make it its own full class but are there enough separate Artificer archetypes to justify its own class and set of subclasses? By far the most disappointing aspect is their Infuse Weapons & Armor ability. Flat bonuses is it? I would add the ability to trade +1 of the bonus to add +1d6 elemental damage (for weapons) or elemental resistance (for shields and armor) of your choice. The damage boost may be always better than the +1 hit/damage boost (maybe +1d4 might be more appropriate, or no bonus damage but an “all damage caused by this weapon is such and such type”) but I’m not a huge math wonk and I honestly don’t take issue with the flavorful elemental damage being a better choice than a boring static bonus. Maybe require a Khyber dragonshard with the appropriate elemental bound to it as a material component (not consumed but suppressed for the duration) for an extra bit of Eberron flavor.
Action Points: These have been obvious since the DMG gave us Hero Points.
Dragonmarks: Oh Dragonmarks. I had hoped this was the edition you would finally break free of the feat mechanic. It has always been a poor fit, and I had hoped the lack of feat chains and feats that improve over time in 5e would finally be the death knell of that marriage. Alas and alack.
I already know how Dragonmarks will be handled in my home campaign and it won’t be through feats. Here’s why I’ve never liked them as feats; the vast majority of 3.5 and 4e feats and most if not all of the 5e feats represent some specific level of training or conditioning. You choose to learn how to most efficiently trade accuracy for power. You choose to pick up a few magic spells, learn how to cast rituals, or study a battlemaster technique. You train your body to better withstand damage or train your mind to better resist magical effects. What you never, ever, ever do in the Eberron Campaign Setting, as it has always been presented, is choose to manifest a dragonmark. It is always triggered by some stressful event (for most members of the Dragonmarked Houses, this is manufactured stress in the form of a Test of Siberys), but for an adventurer it could manifest at any number of stressful circumstances. I have been considering Dragonmarks by way of DM Fiat for years, and then the 5e DMG gave us the perfect way to implement them: Blessings, Charms & Boons.
So while I like the list of spells per Mark, I will bestow them on my Dragonmarked Family PCs the way I would bestow any Blessing or Charm. I would leave the cantrip the same but for the rest of the spells the PC will only be able to cast them as rituals once per long rest. This softens the impact of the PC not having to trade any of their already limited resources for the ability. The other downsides being that any adventurer who manifests a dragonmark is going to see remarkable pressure from their family to hang up their sword and get back to work; pressure that will intensify if and when the dragonmark grows. On the plus side, Siberys Dragonshard items will all require attunement by a possessor of the specific dragonmark. Most of these will be unique to the setting but a few are already present in the DMG (sending stones are the ones that immediately spring to mind).
To balance the rest of the party I would probably make a point to bestow a Blessing or Charm to every PC for completing some personal quest, combining with Action/Hero Points to hammer home the point that in Eberron PC’s are special. Plus if anyone complains too much that’s what Aberrant Dragonmarks are for
Aberrant Dragonmarks: These dragonmarks can manifest at anytime on any person of really any race. The bestow the use of an offensive cantrip as well as a spell that can be cast once per day (as an actual spell, not just a ritual), with more powerful spells being granted as the dragonmark grows (as with true dragonmarks). Spells are learned randomly but occasionally fitting to a theme. The appropriate stat to use for attack rolls or save DCs is to be determined by the DM but as a rule is almost never Wisdom (Charisma is by the far most common, followed by Intelligence). These abilities sometimes manifest independently of the mark-bearer, especially in times of stress, in a similar manner to 3.5 Binder’s Vestige Signs, but sometimes much more spectacularly. For instance, if someone with an aberrant dragonmark that provides fire spells gets into a shouting match at the local tavern, they may see the poor sap burst into flames. These signs can be even more difficult to suppress and hide than the mark itself.
