Very comfortable particularly in older and younger couples. Seeing two old people smiling at one another, holding hands stealing a kiss here and there is a beautiful sight to be seen.
Then there's the young couples. Usually teens, walking down the street holding hands or arm in arm, smiling, laughing, in a world of love all on their own is so adorable a reminder of one's own first love.
Having said that, seeing people groping and tongue lashing and (as seen in some parks at night) engaging in lascivious acts makes me very uncomfortable and I feel is an improper conduct of affection.