I've played around with this for a few hours now. Some of these comments and issues are probably covered and/or explained in the manual.
1. I was a bit disappointed that the map scale was cranked down - no doubt to accommodate the shear size of it - from the original SC2. This wouldn't be such an issue if it didn't strip the feel of WW2 style maneuver from the game. This has exacerbated the original SC2's need to pound a single unit with multiple air and ground attacks to knock it out. It feels like a WW1 style war of attrition, especially in France.
2. Speaking of pounding a single unit to knock it out, Norway is a hell of a lot more difficult to take and China is a tough nut to crack (which I expect).
3. It's somewhat annoying that units can't always move into vacant spaces in China (the jungle square north of Foochow from the direction of Shanghai, for example) or attack in certain directions. These are frustrating terrain restrictions in a severely bottlenecked war of attrition. I'll follow up with the manual.
4. Japan can seemingly became a mighty industrial powerhouse quickly by researching industrial production right off the bat. I was swamped with MPPs early on and used them to max out research and use diplomatic influenced to keep the US war entry low. I don't expect I will attack the UK's assets in the east any time soon. I don't need them (yet). It seems odd for Japan to wield such power while Germany is MPP starved.
5. If partisans are turned off the popup informing the user that there is partisan activity still appears. Not perfect but pretty low on the list of annoyances, that's for damn sure. I expect to turn this feature off every time for at this scale the idea of having partisan units seems pretty off. The designers know better than I do, though. I do wish there was a single check box to turn them all off at once. A custom scenario can fix this though, right?
6. I was suspired when Italy went ahead and declared war on Greece without my say so. Don't I control who war is declared on? I guess not. I'm going to guess there is a check box somewhere where I can turn this off.
All in all, this is a pretty neat evolution from old school SC2. I'm pleased.