How did the Western Europeans perceive and experience the Crusades?

Answer 1

It was seen as a desperate attempt to halt the continuous agression of the Islamic states
Bear in mind that all of North Africa- from Egypt to Morocco and all of Asia minor- from Turkey to Iraq were Christian lands for centuries before Muslims invaded them and eradicated Christianity by fire, sword and slavery.
The Crusades were an attempt to organise a common defense. And it worked too- for as long as the Kingdom of Jerusalem existed - concentrating on itself the agression of the muslims - other Christian lands were left in peace

Answer 2

They thought of it at a righteous religious war against the Muslims for control of the holy land of Jerusalem. The experience was rather difficult for the Crusaders themselves because they wear heavy metal armour in dry, arid deserts.