Windows 8 Upgrade Questions

Hi everyone. :-) Just a few quick questions for the Microsoft Tribe: Have people been upgrading to Windows 8 successfully via the little Upgrade Assistant thing you download from Windows' website? Are there any big issues or whatever that should cause me to postpone my upgrade? I know the water-cooler wisdom is to "wait until they get the kinks worked out," but I'm really anxious and want to upgrade this weekend (as in, right this second). Lastly, if you do the download option (as opposed to the box) is there an option to back up the download file? I don't mean a whole system backup, I mean burn my own install CD. Does that make sense? I have read conflicting information online. Thanks for the help! Saving up for a Surface is my next project. //Mike