unity 5.5 new rotation system?

HI,
I updated unity to 5.5 version and I cant understand the new rotation system…
now I have x,y,z and w?
and why I can put only values -1 to 1?
someone pleas can explain to me this?
although I saw an official video and the rotation system was like the old one is there a way
I can change it to the old one?
thanks in advance.

I think it is a quaternion

you can use ToAxisAngle to get the Vector3