I've found a really interesting article from "Stiftung Warentest". "Stiftung Warentest" is THE foundation which test products for the consumer and gives recommendations based on that, in Germany. Very well known and respected.

The article is in German:
http://www.test.de/themen/computer-t...16516-4116521/

The Link to the google translated page:
http://translate.google.com/translat...2F&sl=de&tl=en

Basically they say, that the antenna design from the iPhone 4 is stupid, that a rubber case on a design-mobile is stupid, too and that other mobiles don't loss signal and drop calls like the iPhone 4.