Against all odds, I really liked this movie and found it quite charming even though I confess that I had to "get past" the quirkiness of the time warp concept which, early on, had my subconscious nudging me "Hey! wait a minute guys!.....". However, having put that to one side, the performances by Sandra Bullock and Keanu Reeves were incredibly sweet and I actually became quite captivated by the whole notion of a "magic" mailbox, etc. The cinematography was very well done and, when Alex takes Kate for an architectural tour of Chicago, the walk was much appreciated here!!
This may be corny: There is a tiny scene in which Kate plays chess with Jack (her canine friend). While not particularly necessary to the "plot", I found it to be a touch of reality that provided an anchor - been there, done that! Well - maybe not played chess with my dogs but they ARE my close companions much of the time. Whether we would like to admit it or not, we have all been lonely at some time or other.
I could be wrong but I don't think this movie will thrill too many guys, but what do I know? The main thing (for me) is that I liked it ... three times so far!