Ok, had a 45 minute session on this.
First impression, it definitely seems like much more of a party game than dance central (and presumably dance central 2). The other first thing I noticed is that it tries to copy the 'swipe' menu method from that game, but it's not quite as intuitive. You can't swipe as fast in this, you have to do it slower and a bit more measured, since otherwise it just doesn't select what you want, so that's a bit annoying.
The move cues are shown along the bottom, with the standard 'coach' you're following in motion in the middle of the screen. The weird thing is though that once the move cue comes up on the bottom, it'll disappear, leaving you to repeat that move (and often it's mirror image) with only the coach to follow. It's not as self explantory as dance central, and although the moves you're trying to do are probably easier than the majority than those of that game, it's actually a little harder here. I haven't delved into the options too much so far, but there doesn't seem to be a training mode where you can spend time learning the moves, or slow down the song, so again that's not so good. The saving grace is that each routine follows more of a pattern, eg, mini routines for verses, choruses, bridge sections etc, so if you recognise that pattern you'll have more of a heads-up with what's coming next. Each routine does seem pretty unique to the song, of the 10 or so that I tried, rather than dance central's repeating of different moves over different song routines.
Each song has two difficulty levels, the normal one, with full body tracking, and easy mode, where it just tracks the top half. It's very difficult to tell how well the game is tracking you, mind you, but so far it seems to be judging me pretty fairly with the standard 'ok's, 'goods' etc. The problem here is that these marks aren't placed centrally, and it's actually rather hard to see how you're doing when you're trying to follow the coach in the centre of the screen. Maybe I'm missing something, but the only place I see these marks for each move is up in the top of the screen, so it's hard to look at that and the coach at the same time. This is a bit of an issue considering that often moves repeat, so you're never quite sure if you're doing them right unless you take your eye off the ball for a few seconds.
On to the better stuff though- the song list is immense, some really good songs in here for parties and fun, rather than the slightly more hardcore listing of dance central. There's a mix of 80s stuff to pretty recent chart hits, and hell it's even got a song from The Nightmare Before Christmas for god's sake. If a dance is set up for 4 dancers (eg, I Was Made For Loving You by Kiss), it'll always have four coaches on screen, even if it's just one person doing it. You stand in the correct segment of the screen behind the coach you want to follow, then you just mimic their actions alone. The Kiss song looked like awesome fun with a full group of 4, with each person acting as a member of the band, the singer gets to pose in the front at times, the guitarist gets to do air guitar, and you often have to do-se-do around the other players. Quite how this will work out without smacking/kicking each other in my small bedroom, I don't know, but if you've got the room, it looks amazing.
To be honest, it was one of the most fun 45 minutes I've had with the kinect yet, and I can't wait to get some friends over to try it out. Even if it's not tracking you that well, it's a lot less staid then dance central when you've got a group of mates back from the pub. Don't get me wrong, I think Dance Central 2 will be great too, it's just that they're two different types of games trying to do slightly different things.
Hope that helps people who are on the fence! Still not sure why Tesco got it to me so early- I only spent £24 on it too, since they had some weird pricing error on it.