I tend to think of the term "like Alice in Wonderland" to mean that someone's senses have been overwhelmed by what they are taking in. Too much information coming from all their senses for the brain to process fast enough to the point that they person is overwhelmed and confused. Something so fantastic that it hardly seems believeable or real.
As an example, take a young girl, who has lived in a small village (and has read Alice in Wonderland") and then suddenly transport her to downtown London.
Sight - Crowded with people, dressed in all sorts of fancy clothes, tall buildings, shop windows filled with exotic items
Smells - baked goods, meats, sweets, vehicle exhaust, etc
Sound - Traffic, horns honking, people talking, construction equipment, vendors hawking goods, occasional bird call, whistling, musical instruments.
Father to little girl upon showing her london "How do you feel?"
little girl to father "Like Alice in Wonderland"