Connecting to the Fritzbox worked immediately and I could easily play on the Fritzbox the phone book. The many features such as email reception and RSS feeds are nice but unnecessary for me.
The only drawback that I noticed in the first three days useful life, is the lighting. This is actually somewhat uneven. However, this does not fall in the dark on (because everything seemed very evenly) but only in daylight. Then the lower part of the keyboard is almost unlit. But I can live with that.
Conclusion: am very satisfied so far and would buy again, mainly because of good coordination on the Fritz box and the so far best design of Fritzfon models.