So, I backed it; ran one of the backer reward adventures last night, and set aside 45min for AAR (After Action Review) with players. Won't focus on module, but system.
Favorite thing? The new Luck mechanic, which replaces DM Inspiration Points. FANTASTIC system that encourages use, building and spending points more frequently, and doesn't end up as afterthought like Inspiration often does.
Least favorite thing? Legendary Resistances remain (I take issue with just denying by fiat a roll result beneficial to the party). Also found a creature with the Hardy trait in the creature book; trait cancels critical hits, which is a huge letdown for player fun, for no real narratively relevant reason.
Player running the new Mechanist class really went to town; despite a little "this is new" confusion, they really had a lot of fun with options.
The Player's Guide had mixed reviews. My table's consensus was that it felt less like its own system, and more like a supplement to vanilla WOTC. Players felt it was a little more crunch than they liked with 5e. I personally felt the crunch was good mechanical support for having variety to options (looking at Fighter, specifically), but no system is perfect for everyone. There were some structural/editing complaints; why were some carryover rules explained, but not others? Stuff like that.
My take? Especially with the Fighter, it felt like a good blend of 3.5 elements and 5e. Still 5e engine, but Traits (Feat replacement) are more INTERESTING, actually adding options/actions instead of just additional proficiencies or moar damage. Replacing Race with Lineage/Heritage allows a little more flexibility. Backgrounds feel more relevant to character design; come with a Trait (selected from a list) instead of the WOTC Background Features that are too situational to use often.
They also just published a conversion guide, so it shouldn't be hard to port in existing 5e options from other sources. Really looking forward to using that for the Cleric, as it only has two subclasses and I have a soft spot for Knowledge Domain.
Overall, I would buy again, but I would change how I presented it to players. I am a longtime fan of Kobold Press, though mechanics of their creatures and player options are comparable to WOTC when it comes to balance and fun/ease of use.
Circling back to Fighter specifics, and why I compare this to 3.5/5e blend: Fighter brings back the "Improvements" (ASI) at every other level, allowing them to max stats quickly and get more Talents. BUT this isn't the same as 3.5's issue with Feat selection, as TOV Talents aren't just "+2 to this roll" or similar. Talents each come with a few bullet points, offering a breadth of applications and adding interesting options.
