This tech note from the iOS Developer Library contains pretty clear rules about how to arrive at the "app name" portion of the link:
To create an App Store Short Link, apply the following rules to your company or app name:
Remove all whitespace
Convert all characters to lower-case
Remove all copyright (©), trademark (™) and registered mark (®) symbols
Replace ampersands ("&") with "and"
Remove most punctuation (See Listing 2 for the set)
Replace accented and other "decorated" characters (ü, å, etc.) with their elemental character (u, a, etc.)
Leave all other characters as-is.
Punctuation characters that must be removed.
!¡"#$%'()*+,-./:;<=>¿?@[]^_`{|}~
There are also some examples to demonstrate the conversion that takes place.
If you follow the rules, you should be safe in using the link for production.
EDIT:
Having said that, in my app I use this scheme to get real fancy and open the Rate page directly from within the app :)
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?id=<YOURAPPID>&pageNumber=0&sortOrdering=2&type=Purple+Software&mt=8"]];
Disclaimer: Use at your own risk, of course, I don't think there is any guarantee that this type of link won't break in the future.