Since I've got my Windows Smartphone, I tend to miss quite some calls because the thing does not ring or rings too late. In that sense, it makes me save time
In the end, it does save me time, but not as much as my good old Psion PDA used to.
But you can find some good add-on programs, I'm using a database programs and have hundreds of cards with various information in there. That way, when I have my phone, I have about all I need to know, wherever I am (I do make backups...).