Well I highly doubt we will ever see a 25 minute demo and even if they released a demo I would skip it and just purchase the game. I know SSM is helping them with the game and I also know that Mr.Weerasuriya has said there are gameplay mechanics that they are waiting to show off. We have not seen everything and I don't blame them for keeping their cards close to their chest. This extra time will allow them to polish the game further and possibly add more content.
The thing I am most concerned with is more open areas, I know its a linear game but that does not mean they cannot have an area like the one depicted in their concept art. As far as I am concerned this MUST make it into the final game
I can see it now a scene in a crowded train station with a cathedral styled (Destructible) glass ceiling and Lycan's killing pedestrians while the train is pulling into the station, you have to jump on the train to escape them and then the fight continues in a closed train cart as you make your way to the conductor ..... destroying seats and ..... never mind I will stop now.