I've now begun to read through the How To Play document and skim the DM Guidelines document. Again, note, these comments are given without having actually played. Also it will help to have your copy of the playtest documents handy to comprehend some of these notes.
One thing reading through the Dm and How to Play docs did was clarify the Rounds vs Turns thing a slight bit. Yes, there is some mixed use, but the intent to use rounds instead of turns as the combat time period has been made clear.
Something that really sticks out to me favorably is how they are handling the Conditions. The clear way these are described and the mechanics work is well done thanks to how the Advantage/Disadvantage rule functions.
Ethereal appears to be taking the place of non-corporeal.
Invisible still leaves me wondering a bit about the DC to detect and locate the invisible character or creature, but I am not anywhere near as skepticle as I was during the rumors and leaks phase of things. It appears to be an opposed roll from the reading.
Frightened is good. Fear has always been tough one to cope with for a player and sometimes inconvenient for a DM. This version simplifies it greatly.
Intoxicated is one I want to see in actual play. I'm not in favor of the "buckets o'hit points" so I'm inclined to think a lower die type of damage resistance might work better for what I see as D&D feel. A d6 seems high. This also might be abusable. Testing required.
The Death and Dying rules are geared toward the "bucket o'hit points" style characters, but they should work fine, especially for more story intense games.
Under the Heading "Healing" the rule listed is almost identical to a house rule my campaign has been using for a year. The only difference is my rule has characters healing from 1 hit point and the Next version is healing from 0 hit points.
Hit Dice and rests. This doesn't stike me as having a D&D feel just from reading it. It seems to be too far into the risk averse category of play which takes the tension and anticipation away from the game. Without risk there isn't much reason to plan or prepare, or be concerned with failure. The planning, prep, and concern is a big part of D&D for me.
Under Equipment and Money, it looks as if the rumor of going to the silver standard might have been just a rumor. The gold piece standard remains intact.
The way armor and Dexterity modifiers works seems broken. While someone without good dex will benefit most from heavy armor, having a good dex makes it a better deal to go with the higher end of the light armor. You have the advantage of lower weight, better mobility, lower cost, and in many instances better total AC compared to people in medium and heavy armor. This definitely needs work.
The inability to lose a spell when clobbered by something while casting doesn't appeal. Doesn't feel like D&D to me. Again, another risk averse, "I don't wanna lose" mentality. It would appeal more if the character had to make a check to avoid losing the spell instead of never losing the spell. Give it some drama.
I won't go into the equipment list yet since there really isn't much of interest, and there's not much I want to discuss yet on spells with this minor exception: Turn Undead is being tested as a spell instead of an ability. (Have not read character sheets yet.)