So browsed Amazon and ultimately chosen also because of the good reviews for the 6303 classic steel.
The focus was in addition to the usual requirements such as excellent voice quality, long battery life and well-structured user interface now on a balanced display keyboard for money, so that you can easily operate the phone with one hand (after all, learn from our mistakes).
After a few days use, I can only say: Yes, the Nokia 6303 fulfills these requirements perfectly. The well-known by Nokia, intuitive menu, excellent voice quality, the phone looks really chic, is not so tiny that you have to hold it while calling times to his ear, even to his mouth;) and yes, it's very good single-handed use.
My conclusion: For anyone who wants to make calls with high voice quality and also primarily requires the phone about it only for SMS sending and have done without loving to all the pesky gimmicks of many cell phones, will be the 6303 certainly very happy.