For no one's gratification but my own, here's my impression of some Kinect demos...
Steel Battalion
Didn't even get past the tutorial on this. Ambitious idea, pretty rubbish execution. The interplay with teammates in the 'vertical tank' seemed intriguing, and the idea of having a plethora of levers etc at your command is all very steampunk and inviting - but it just doesn't work. It took me about 3 goes to get each motion to kick in (and when this involved flipping open multiple panels to access further levers, the frustration was multiplied all the more). And that was when I was up against cactuses for enemies. The gesture recognition was just too poor - with too many comparable poses in close proximity. Might give it another quick go in the live game, as it did have an interesting vibe, but looks like a big miss overall.
PowerUp Heroes
This was fun, but also pretty unchallenging. Seemed to just be a simple mix of punch-n-kicks (but with no block function, no real skill), a basic strafe dodge, and a collection of special moves. Those supermoves are a good laugh to execute, especially the 'prepare a fireball'/Street Fighter style ones - and the move detection was snappy and all the poses very intuitive (with handy on-screen mnemonics). But ultimately the core fight mechanic seemed too simplistic for this to have any legs. Good for working up a quick sweat though in a cartoon fight environment.
Wreckateer
3D angrybirds, with a decent kinecty-twist in that you can bat at the balls mid-flight and alter their trajectory. All the reviews suggest the levels stay pretty samey, and the replay value is low. Didn't quite grab me, mainly coz it seems that it didn't really matter how accurate you were on the early levels - everything just exploded. Also the 'flying shot' that you steer early on seemed very unresponsive. Kinda diverting, but didn't seem worth a buy really.
Star Wars Kinect
The racing game on this was pretty generic and gained nothing I could see from being steered with outstretched arms. The lightsaber battles were very clunky, as you're basically recycling 4 moves, all of which were a bit unresponsive and not very creative (block lasers, swipe with your sabre, rush forward and force grab). The latter surely has room for being good with kinect, but it just seemed really unresponsive and limited.
The 'Rancour Rampage' section was the closest thing to a fun mini-game. It almost felt like it had nailed the 'moving through a 3D environment with body detection' - with the one major foible that I couldn't get the 'rush forward' move to engage reliably - so I had to hop to progress. Demos often lack decent tutorials, but this one totally needed a full one to work. Shame coz smashing buildings and grabbing droids was kinda fun. It actually had a fun range of inputs that were mainly responsive. I just needed to know how to move forward
Kinect Sports 2
Tennis was fun, but fairly loose, and not that much different from the (snappy and exciting) pingpong in the previous game. The golf on offer had that intriguing glimour of what supplementary-kinect could be like though - raising your hand as if shading your eyes to look down the course was simple but effective, as was asking for a club verbally. Aside from that putting etc had such strong visual guides to make up for lack of fine-accuracy (altho the little sidesteps to to line up were recognised well) it seemed a bit challenge-free. No nuanced rolling maps of the green here.