First 30 mins gameplay. Spoilers etc.
I'm assuming this is pre-production gameplay footage because it's definitely NOT the first 30 minutes of the game I've been playing. You don't meet Elizabeth until about and hour and a half in for a start. Literally everything is different, from the way Elizabeth looks, the HUD, even the storyline has been completely changed.
As for the actual game, it's very good, I'm about 6 hours in so far. The skyhook is a great addition and means some of the battles can take place over huge areas, meaning a massive amount of variety in methods/angles of attack. It's also a brutal melee weapon. The story isn't quite as involving as the first one but it's still pretty good. Rapture was prettier too, even if it was falling apart. I'm slightly disappointed with the variety of vigors (plasmids in the first 2) as I seem to just be using the same 2 in pretty much every situation. However there's a fair range of weapons to choose from, but only being able to carry 2 at any time can be frustrating.
I'd give it a solid 8.5, maybe even a 9 from what I've played so far, but for so many places to be giving it a perfect score seems a little generous.