Is the Sony ericson c903 good?

No. Sony erricson c903 is just another of sont erricson's slide handsets designed to look good on paper, then practicly self-destruct as soon as you take it out of the box.
Stay away from this phone. If you want a good phone in the same price range, try the LG viewry GT or the blackberry curve 8520.You would be much better off with either of these