I updated my iphone 4s to ios7 without issue, then I got my iphone 5s and restored from my 4s' backup. Everything worked smoothly and great, except that one of my calendars had their color changed (from orange to purple). Now I already have a purple calendar, which is why this is problem. I have attempted to change my calendar color several time, and I get no error and it look like it works great but a few seconds later it changes itself back to purple. Not the most critical bug, but very annoying. I have attempted to change the color both on my phone and on icould.com, but neither work.