Comment by pfranz

Feel free to continue using Snow Leopard if you're happy with it. Here are a few things I've liked in subsequent releases (sorry if some are actually in Snow Leopard and I forgot):

  * Notifications
  * Air Drop
  * Face Time
  * Native Full Screen apps
  * Multi-touch gestures (mostly use with multi-desktop and  fullscreen apps)
  * Mac App Store (I like it better for OS updates)
  * Recovery Partition
  * App Resume
  * Terminal improvements (I stopped using iTerm)
  * Air Play mirroring
  * Notes (and syncing with phone)
  * Compressed memory
  * Full Disk encryption
  * Improved multi-monitor support
  * Spotlight improvements

A few things I'm looking forward to when I do upgrade my hardware:

  * updating while asleep
  * hi dpi monitor support