Well, I just got done playing through the demo for the night, so I guess I'll give a little review.
Story: I'm not going to give anything away, but the story was alright. The first two levels were pretty simple, and the story was intriguing. From the two levels I got, I didn't see any major breaches of canon, but then, I also didn't see the Flood or much else, so that may be why.
Skirmish: This was actually a lot more fun than I expected. I had my reservations about the system, and while I still have my doubts about the socketed bases, I think the economy is just right. Because the controller limits your ability to macromanage your army, it would be too difficult to micromanage villagers. I'm not a fan of the spoon fed economy as an idea, but I think Halo Wars did the right thing with the economy. As for units, while it felt slightly rock paper scissory, that's alright. Overall, the unit balance was pretty decent, though the über units were obviously much more über (once I got a Scarab, the UNSC was pretty much finished). At least as far as the Covenant go, Skirmish is pretty fun and pretty straight forward.
Use Interface: This was really important to me, since it was really what defined Halo Wars as a successful RTS on the console. The way I interface with the game is key to how well I can play it. And the user interface wasn't all that bad. Sure, I prefer the good old fashioned keyboard and mouse to the controller, but at the end of the day, Halo Wars gets the job done. The circle menu is simple and easy to use, clearly an act of pure genius as far as UI goes. There were a few little things, though, that bugged me. From my brief experience, there didn't seem to be a way to select multiple units precisely. In a PC RTS, for example, if you hold shift while selecting units, the previously selected stay selected. While Halo Wars offers the paintbrush select and the double click select, as well as an all units and on screen units buttons, it it either doesn't offer a precision multi-selection or the button is intuitive enough for the average gamer to figure out easily. This makes selecting certain units out of a group a bit harder. The other thing was that while Y-abilities had cool downs, I couldn't find any indicator, so I never was really sure when a Y-ability was ready to use, and had to just hope.
Canon: The all important canon, which was and is one of my primary concerns. I already stated I didn't see anything wrong in the story, but then, the glimpse of the story is very brief, and the levels very simple. You get Marines and Warthogs and fight only basic Covenant units, and that's about it. A plus from E3 07, I noticed that explosive damage has been increased a bit, so that you don't sit there pounding away at a Warthog with a fuel rod, and have it just shaking about hit after hit. However, there were a few things I noticed in multiplayer that I'm assuming will be in single player. Probably the biggest is the presense of shields on the SPARTAN-IIs. The MJOLNIR Mk.V, the first variant with shields, wasn't invented until 2552, and as this takes place in 2531, shields on Spartans in campaign would be a breach of canon. It sounds little, but in the grander scheme of things, it cheapens the feeling of just how amazing Spartans are, when you consider how long they were in combat with only two real KIA and one WIA prior to Reach, all without shields. And, obviously, there is the Spartans vaulting through the air to jack aircraft, which I don't think is the right direction to take either. I didn't notice a lot of problems on the Covenant's end, but then, I have only played as Regret (since the other two leaders, who appear to an older Arbiter and a Brute Chieftain) so I can't be certain. And I only played two matches (the first ended fairly quickly with my defeat, because I was new to the game and wasn't sure how to proceed or what units to use against what; I didn't build many units to start, got infantry rushed, managed to repel that somehow, built quite a force of infantry, got tank rushed, managed to repel that too somehow, but finally the UNSC player got two tanks and five hornets over my base, and they'd just eat any units I built; the second match took much longer, and while the UNSC somehow managed to Vulture rush me in the beginning, I had fortunately built a secondary base, which I managed to defend once I got the hang of things, for an eventual victory), so I could have missed something. I'll have to play a few rounds of Skirmish as the UNSC, but overall, the canon seems decent. The Spartans are really the only thing off, and if the shields don't appear in campaign, it should be all good.
I like pi.