I think it varies from person to person, and trip to trip. When travelling astrally one needs to keep in mind that you aren't moving in a physical sense. That means a lot of the things that make senses like touch and taste work aren't being used the same way.
One of the main factors is how deeply you manage to go into the astral. For example, someone who is meditating lightly and still partly aware of their physical surroundings might just be 'poking the head' into the astral by shifting only the conscious attention. So you might only see and/or hear things. like remote viewing.
Other times a person might successfully drift away from their body but stay close by or closer to the material level, so you might be able to feel and sense a lot more of your own body but not really be able to reach out and touch things and feel them in your hand.
Or if you manage to separate from your body and shift consciousness to a higher/more energetic plane it may become more dreamlike, with sensations of flying, conversing, or connecting with other locations that you can feel and smell and touch as if you were there. Like meeting a spirit guide in a green place that reminds you of a secluded glen or something.
In the end, however, one thing to keep in mind is that if you do succeed in travelling astrally, you are existing as energy, in a place made of energy, and guided by your conscious mind which is only used to interpreting the world through physical means.
Usually what happens is you feel or see something as a sensation, an interaction of energy, then your mind goes "This feels like..." And tries to build a reference or image to match the vibrations. So really most sensations come less like places and things and more like emotions, impressions of images, temperatures, etc. This also means that what you experience is always influenced by the things you are already familiar with by simple rule of association.
You might feel like you are in a narrow or dim place, that might seem cool or slightly damp, but safe, and deep. So you might form an image in your mind translating the place as a cave. Another person might form an image of a stony hall. A third might think of a wooded glen at night. You aren't physically surrounded by stone, or wall, or tree, but you feel like you should be so that is what you interpret from where you are.
What Spirit75 said :) With me, it depends on the trip, and it depends on if my guardians are with me. If my guardians are with me, my experiences are more...crystalline... and vivid than if I travel myself. I get flashes of color, textures, smells. Depends on where I'm going, too :)