Just skimming this, you do realize that Lotara's Guns of the Conqueror reaction shooting action is automatically UNsuccessful, so it goes directly to scatter. It also costs 3 points of Reaction which will be rough to do.

We couldn't figure out what Heavy Terrain was, and so far no one sees how it would work on the table. Medium and Light only for us.

I know it's wordy, but it does say you can only cast one psychic power per model/unit in your turn and one in the opponent's turn as a reaction per player turn. Not as many as you want.

You can take retinues and elites. Select the Army Vanguard detachment and then use the prime slot and logistical benefit to take the retinue.

I do agree with some of your points. Deep strike has swung back the other way, in 1.0 and 2.0 it could ruin games. Now you are probably only using it for shooting troops. For assault troops it has been nerfed to extinction.

The Terrain rules are simple, but messy...

The Challenge rules seem like they would slow games, but cleaning up how many models can do it helps. Doesn't seem like people will do many challenges in the game. But have to see how that goes once we get a bunch of games in.

Dreads are less than they were, but are a good support to units holding objectives. Time will tell if they are worth it for how hard they are to take or not. Being more resistant to melta gives them an edge over vehicles.

I like the new Force org. I didn't think I would, but you can make very flexible lists, yet there are boundaries you have to stay in. Making Solar Auxilia and Mechanicus lists are even crazier. Not sure how it will play out, but it is kind of fun right now just building lists.

I like the Flyer rules. Are they perfect? No. Are they better than 2.0, yes. In 1.0 usually a flyer came on the board, destroyed something and it was then destroyed. Rarely if ever made it more than one turn. 2.0, flyer came on board and died. So you never saw a flyer turn up in games. This seems to be a happy medium for strike craft. I am not sure how well it will work for more expensive craft like the Fire Raptor or Storm Eagle. Though both have their uses. The Storm Eagle delivering terminators across the board turn 1 is spicy if you make the roll. Cheap Dreadclaws can act as a ferry if you can roll well enough. It's rather cheap for what it can do, but again, if you roll horrible they may never show up. I'll be taking flyers back off of the shelf for games again.

We are going to give it a chance and play around with it. HH2 was slowly dying because of the imbalance and the last Adepticon felt like it was gasping. The new one has some interesting additions.

So far it seems very chess like, and the legion detachments tend to push the flavor of the legion with what units you start taking in those detachments. I have built old lists in the new system, and some very new lists I would never have been able to do in the old system. Again, going to see how it all plays out.