Overall: I like it. The classes all have a nice feel to them, and it is very easy to customize (both in terms of choices you make and creating your own custom elements). For example, my friend is interested in a Cleric of a Nature god, and we both quickly saw that we could just make it ourselves.
Replacing martial damage dice and the damage bonus with Deadly Strike is great. It keeps things simple and at the same time is fun (everyone likes rolling more dice).
The unified spellcasting mechanic is great. Like Deadly Strike, it is simple to use and fun.
Barbarian: I like that they can rage 2/day at level 1, as this is really the defining feature of the barbarian. The requirement to attack a hostile creature and lack of reactions are pretty good drawbacks to counteract the really nice benefits. I’m not sure about resistance to physical damage (it seems like it might be too good), but I will have to playtest it to really see.
The rest of the features are nice. They have a great primal feel while at the same time don’t force that concept. If someone wanted to make a purely martial barbarian there is nothing here that would prevent it.
Cleric: I like the increased weapon attack bonus. Keeps them a bit behind Fighter, but not too much.
I like how the domains all gain turn undead or control undead as a bonus channel divinity option.
Druid: I love the two paths. All druids get utility wild shape, and then you pick between improved spellcasting or wild shape as your attack. Very similar to the 4E druid.
Not being able to switch back and forth between forms is a bit limiting, though. I would prefer something like this:
“You can use your action to revert to your normal shape earlier. Doing so reduces the duration remaining by 1 hour.”
This way, a druid could turn into an animal (for the benefit) and then turn back in order to cast a spell without fully ending the wild shape.
The different animal forms are great, exactly how I wanted it to be handled. It makes it very easy to use because you don’t have to go flipping through the Monster Manual to find your new stats. The Enhanced Form features are very cool.
Fighter: Expertise is a cool mechanic, especially with gaining new uses for it at higher levels. I think it might be nice to allow more than one die to be spent at a time, giving Fighters the choice between going all out and a more balanced approach. (Use the old “roll them all and use the highest” mechanic.)
I know some people don’t like the bonus feats, and I had the same initial reaction. And then I thought a bit more, and realized that this objection didn’t make sense. Rogues get extra skills. Past versions of the rogue simply got a bonus background. And yet I don’t remember anyone saying that this was dumb because anyone can just spend feats to pick up extra skills. Feats are a limited resource. Fighters get extra feats alongside many other bonuses. If all fighters got was bonus feats I would say it was a bit boring. But right now, fighters get almost a full second specialty (3 feats) on top of other cool features. I find that pretty awesome, in the same way that rogues getting extra skills is awesome: it frees up character options. You can use your 3 bonus feats for a fighting style specialty, and then use your actual specialty for something else if you want (like skills, or magic, or whatever). Or you can go all out and use every feat for martial combat.
Death Dealer: Richochet and Wide Arc are cool, I like both of these. Strike Command and Deep Wound are basically the same, but Strike Command uses your reaction. Seeing as how all of your Superior Defense options use your reaction, this makes Strike Command a bit worse in my mind. Slam seems too good, as it does the same damage as Deep Wound plus imposes disadvantage.
Superior Defense: I like these ones. Does Warning Shout work like the others (in terms of using it after seeing the result of the attack roll)?
Unerring Attacker: nice choice here between a big bonus to the attack roll (before you roll) or getting a chance to deal half damage on a miss or turning a missed opportunity attack into a hit.
Multiattack: I like how this works, it balances nicely with Deadly Strike. I think it would be cool to allow a bit more flexibility with it. Instead of requiring the player to pick between one big attack and a bunch of little ones, I think it would be cool to be able to distribute your Deadly Strike dice among any number of targets. This is already what you can do at level 5: attacking one creature for 2[W] damage or two creatures for 1[W] damage. At level 15, it would be nice to be able to make two attacks (for 1[W] and 2[W]) in addition to one at 3[W] and three at 1[W]. But this is easy enough to implement on my own. Also, it isn’t clear how Multiattack combines with Two-Weapon Fighting. Would you get to attack each target with both weapons?
Unstoppable: Nice choices. 'Nuff said.
Monk: Where is Flurry of Blows? Other than that, it looks good.
Paladin: The three types are great. While I personally don’t care for alignment restrictions, it doesn’t interact with any of the mechanics, so it is easy enough to ignore. I really like how the Paladin isn’t linked to the gods, but instead is about living up to some sort of ideal. A good Fighter/Cleric design while still being different enough from both to seem unique.
Ranger: Favored Enemy is perfect. I can’t wait to see more examples. It is flavorful, easy applicable in many situations, and makes it easy to design custom ones. I like that the Ranger (and Paladin) begins getting spells at level 1.
Rogue: Seems a bit more balanced now, with combat prowess not quite at the level of the Fighter (with reduced attack bonus). Getting 2 bonus skills instead of 4 is good, and I like the three bonus feats as part of the schemes. This gives each scheme a nice focus. I also like how each scheme has its own way to get advantage pretty easily.
Sneak Attack: at first I thought it was odd, because you get disadvantage. But then I remembered that each rogue can very easily gain advantage on an attack. So you are just trading out accuracy for damage, which I think is cool. Being able to attempt a sneak attack even without advantage is also nice (I don’t think I would ever do it, but I like that it is an option…I know people who like to go all in every time).
I also like that they get their own unique multiattack options.
Wizard: Not many changes here, but I like them. Arcane recovery plus lots of spells slots. Good times. I still think that Evocation and Illusion should be able to prepare extra spells (even if they just get a set list like Clerics), but I’m not too fussed about that.