Okay heres the full rundown people.
The demo had quite a few flaws still but the patch 1.1 is already out and it fixes most of these. Hoi3 so far has mostly disappointed by being somewhat harder to run than expected. Some high-end hardware like mine had compatibility issues with the demo and i was quite puzzled for a day or two.
However now that the game is out (Amazon shipped copies are arriving, Gamersgate will open it up tomorrow morning), people who were able to patch it says most of the issues are gone. Patch 1.1 did wonders though there are still small oddities that I just cant explain (Stalingrad is misplaced, Whiskey Tango Foxtrot?!?)
However, overall, its a huge improvement over HOI2 though it sure has a learning curve. The realistic military hierarchy they implemented, with Theaters, Army Groups, Armies, Corps, Divisions and Brigades is great for history buffs but its sure a big change from moving stacks of doom around the map.
As for ahistorical results, its clear that theres still some balancing to do. The demo ran from Sept 39 to Jan 40 and heres what someone was able to achieve:
Yes this is America getting overrun by Panzers. On the eve of 40. Following the fall of Poland, France and England, of course.
This is the most extreme example, but even I was able to pull a 39 Sealion, and everyone and his mother took Paris in 39.

Oh and I also managed to make the US join the war on my side. And Ive seen Italy capture Baghdad, Cairo and Kuweit on its own.
Id say this is full of potential though. Ill probably wait till the first expansion to buy it with XP1 and play a torrented copy till then. Im all for encouraging small developers like Paradox but I dont pay for games twice; plus I still have doubts regarding performance issues. More tests are needed before I open my wallet.