The K550i is an excellent phone for its price(i paid 7100) in dec 07 and after 3 months, it still looks and works like a new phone. The features are excellent, the camera is class and the phone itself is not Orange in color!
I am especially pleased with the no-frills features that this phone offers. The bluetooth, 2MP camera, the music player(not as great as the walkman series) - this is called the camera series by the way, editors etc
The camera unlike previous creations from the Sony ericsson stable is surprisingly small and light weight. One thing I liked so much is the flash light, I once used it comfortably for 45 mins at a stretch to read in a night bus and surprisingly- the lights do not drain the battery. The Disc2Phone software too is a very user friendly interface that aids file transfer from and to the phone.
The sound system in this phone could have been better both in terms of intensity and quality. The camera series phone need not necessarily have a poorer audio feature.