So a few bugs and problems I noticed.
Bug 1:
I was bombarding a planet that the Tyranids had completely wiped. I nuked them down to 0, but the next turn they went back up to Moderate again. I don't know if that is a bug, because it might have been reinforcements from other planets, but it was weird. What is do know is a bug is this: I wasn't able to bombard them again, because every time I tried it would just say I was targeting "Imperial Forces", even though there were none left on the planet.
Bug 2:
For some reason it wasn't letting me select a Marine. I suspect it's because there is a blocker stopping you from selecting guys on different worlds and the like, but I couldn't find were my previously selected guy was. It looks like it didn't get cleared correctly.
Issues:
Confirmation on naval battles when you accidently attack imperial forces would be nice. I miss-clicked and screwed myself.
Attack, Raid, and Landing aren't clear, there should be obvious differences between them. It's really weird that Raiding reduces the forces by 2 when you fight less of them? It's just unclear and strange. There should be clear disadvantages and advantages to all methods. My suggestion: Attack should land selected forces on the planet. Any battles done with forces on the planet would reduce the current enemy force strength by 2 or 3, instead of 1, but it would also have you fighting a lot more. Also add an option to "Return to Transports", letting them return to the transports they came from without too much micro. Raids would lets you plink at stronger forces and get out of there before they could mass up and kill you, reducing the force only by 1 at a time, and also still letting you bring some vehicles (Like bikes). That way, there are two methods of attack: Landing, or lightning raids, and it's far clearer what they do.
A level of Orc forces is much weaker then the equivalent level of Tyranid forces, for some reason. Seems odd.
I started a game with an extreme Tyranid infestation on my Recruiting world, as a fleet-based chapter. There was nobody left. Kind of annoying, seems like your recruiting world should be immune to starting like that.
So other then those issues, it's been vastly improved and hugely fun to play!