My Feedback is pretty well in-depth:
I have played the first Halo Wars on Xbox 360 and really enjoyed it. When I first played the Halo Wars 2 Beta (on XB1) I was a little suprised at the gameplay. In my opinion, the graphics look brightly cartoonish. The Beta map seemed more bright and vibrant than in the original Halo Wars. I think Bases in the original game look more realistic than in the Beta. In the original Halo Wars the graphics seemed more realistic to me, like you were seeing a real battle -just in a zoomed out view. I definitely prefer the darker military colors for units aswell (which is what the original game has). So for Halo Wars 2, the graphics in my opinion seem worse than the original Halo wars.
Also, the Camera in Halo Wars seemed more flexible. However, as far as I know, in the Beta you can only control the camera with one joystick, unlike the original Halo Wars where you controlled the camera with 2 joysticks. I think this is a downgrade for the Beta.
Another suggestion is to make the game more responsive. In Halo Wars when you selected a unit it would respond to you loud and clear with dialogue. In the Beta, however, you can barely hear life from your troops. I think this should be switched to how Halo Wars did it. Another way to make the game more responsive would be to make "marking" more visible and noticeable. In the original Halo wars when you sent troops to a location you would have set a mark on the spot where you would want them to go. This mark (in the original Halo Wars) was much more noticeable, compared to the Beta. It was blue and bright. In the Beta it seemed to me barely noticeable. Also, I don't know how the story will be in Halo Wars 2, but in Halo Wars multiplayer the updater voice was a man voice, aswell as Serena (Captain Cutter's AI assistant). I suggest, when the game comes out for Halo Wars 2, allowing a character from the story to be the update announcer (whatever you want to call it).
I know there will be other game modes and maps when the game comes out, but I suggest making a long-timed game mode (if that hasn't already been considered). I like playing long games.
Also, what happened to the vehicle units the Elephant and Cobra? I really like them aswell as the gremlin (but I'm guessing in the Beta since we could only play as Captain Cutter, he does not have the gremlin unit). I know there's a unit called the Kodiak in the Beta, but I would much prefer the good old Cobra.
Back to Graphics, in my opinion, unit details in Halo Wars were much better compared to unit details in the Beta.
Another suggestion, I didn't much like the cursor in the Beta. On that bright map, it was sometimes hard to find immediately.
Also, just like in Halo Wars, at the end of a battle you should be able to scan the battlefield and get battle statistics like casualties, combat effiency, etc.
Also I think there should be building percentages so you know how soon a building under construction will be ready. There should also be a queue for constructions/upgrades, as this was the case in the original Halo Wars.
One more suggestion, I think the default controls should be that or almost identical to the controls in the original Halo Wars (Which in the Beta, it pretty much was). However, I think you should be able to customize your controls down to point where you decide which button does what. I prefer the button LT for fast moving than LB.
In conclusion, I know some of the things I've said you guys may already be working to improve. My main concerns/suggestions: The graphics, controls, and Halo Wars Feel. This is a military strategy game, so the bases and units should reflect what a military would look like- not bright red and blue, but a dull red and blue. For controls, when selecting something, I think the selected unit/building should be outlined better. In Halo Wars the outline (I think) of a selected building was white or yellow. This worked fine since the contrast between a dull colored building and a bright outline was noticeable. In the Beta, however, there are bright colored building outlines with bright buildings. The contrast is less. Most importantly, I know some say Halo Wars was an incomplete game, but it was still fun to play. It was unique and I hope this sequel keeps the Halo Wars feel. Thanks for reading.