i think it was from a guy who knew how much I cared about him it would be amazing. if however I didn't really know or like the guy I would be a little put off as I think in this day and age love letters are something so intimate and powerful and really should be used appropriately. I think if my boyfriend did that (not in a million years lol he's not very good with expressing his emotions on paper) I would be so so so touched as I'd know how much courage it'd take him to write it. I wrote a note for my boyfriend right at the beginning of our relationship, two years ago, telling him about my night and what I wanted to order for food, drew little pictures, gave it to a friend to pass onto him (we lived in college dorms) and he's kept it in his wallet ever since. If something like that could mean something to a guy, especially my boyfriend then think what a proper hand written love letter could do to a girl! My tip would be to use it at the right time, not out of the blue but let it serve a purpose whether she's going away on holiday, going through a bad time, or deciding on the next step of your relationship. I really hope you do it!