I tried to upgrade on day one resulting in a buggy and broken system. I believe this is actually application incompatibilities. Yesterday I performed a clean install from usb flash drive following http://osxdaily.com/2011/07/08/make-a-bootable-mac-os-x-10-7-lion-installer-from-a-usb-flash-drive/. Now Lion works great. My recommendations: 1. Do a clean install of lion, not an upgrade. 2. Check for new versions of the applications that you use and install one by one instead of restoring applications from time machine. 3. Repair disk permissions 4. Don't judge the operating system's battery or speed until indexing is done. I hope this helps someone.