I've had a go with the new paints, as have plenty of others out there and I thought I'd add my thoughts to the rest.
Base - much like foundations, perhaps a little smoother and apparently have a different medium which won't separate as much when diluted.
Layers - also similar to the old paints, but with a slightly higher pigment concentration to provide better coverage, and using a similar medium to the bases for less separation.
This is when it starts to really get new
Shades - these are replacing the washes, but behave quite differently. They have a completely new medium, and the tones are also different. This results in a wash that flows much better across the model, doesn't pool in the way that the old washes did on flat surfaces, and gives a more graduated shading to textures. It also tastes a lot better (when I learned my painting, it was in the old days when even GW employees taught you to lick your brush to keep a point and I've never been able to kick the habit), much like the old inks.
Glaze - a brighter, less heavily toned version of the shade, only comes in 4 colours, but can give a tint to other colours and metallics. Probably of limited use, but I can see it being useful to recover the colour of an area that has been over-highlighted, and might be good for shading very light colours.
Dry - extremely thick paint, you can hold the pot over your head without worry of it coming out. Actually a good idea as you'll waste a heck of a lot less paint when dry-brushing, and the pigment is very concentrated which helps.
Textures - Not too taken by these, just paint with some sand in it, and when I tried it you really had to pile it up to get good coverage of an area.
Colours - they've changed, just look at the conversion chart, some of the new colours are supposed to be the same as more than one of the old colours, so they can't be exact matches. So other than needing to re-buy a lot of colours for upcoming projects, I'm really rather impressed with the new range and think its a good thing they've done.