I've been using an iPhone5 for almost a year to the day and I've been more than happy with iOS6 up to this point. It's snappy and responsive and everything works as it should, for the most part. This will be a direct comparison review of iOS 6/7 and it's goal is to sway you to upgrade without a second thought.
The update process was pretty straightforward, update iTunes 11 to 11.1 and restart for changes to take effect. After plugging in my iPhone, it immediately prompted me to download and update to iOS 7. The download took a little while, about 45 minutes, which I suspect is because EVERYONE and their dogs are trying to download it at the moment. The whole process took about an hour, I didn't lose any data, contacts, music, apps, etc...(As an aside, you COULD download iOS 7 OTA but it requires 3gb of space to do it, screw that!)