I have been using Linux Mint 9 64 bit for 2 months.
I switched to it from Ubuntu 10.04 64 bit.
I prefer Linux Mint 9 to Ubuntu 10.04.
Things I like about Mint 9:
The Mint menu. I prefer it to GNOME's default menu bar or menu.
The default software selection is better than Ubuntu's.
I like that it comes with GIMP pre-installed, and also that it has Pidgin instead of Empathy
The Graphical GRUB menu.
I know I can get these things in Ubuntu 10.04 but I prefer to have them out-of-the-box.
Things I like about Ubuntu 10.04:
I like Ubuntu 10.04's default themes and icons better than Mint 9's default theme and icons
I have installed Ubuntu 10.04's default themes and icons on my Mint 9.
I plan to try out Linux Mint Debian when it has a 64 bit version.
I want to thank the Linux Mint creators for making a great distribution.