Soft, smooth and slippery on the outside, textured and firm close to the pubic bone, the opposite side is very elastic, once past the opening, there is more space, it is very soft. Deeper in, the cervix dome feels a bit firmer, similar to erect penis glans' firmness, it feels a bit tighter beyond this point.
When a woman is orgasmic, there is a lot of movement inside, the inner vagina does something called "tenting" the space inside expands to the size of a tennis ball, this state is usually followed by an orgasmic muscle contraction which feels really tight on your dick.
The vagina feels different in different positions, it can feel shallow, deep, tight or loose. The thing that really turns me on are all the different kinds of orgasms that are possible including the squirty ones.
Another thing to add is that it feels different depending on the time of the month, sometimes her juices are thick and creamy, others they are watery and transparent.