The issue with phones is usability, as always. Even if you find a phone that does a good job as a phone it doesn't mean that the music part is good and/or caters to your needs. I have a Nokia E51 now that actually does a superb job as a phone for the most part. In contrast to the "N" phones it is nicely made using pleasant materials. It also has very good Mac and iTunes/iPhoto integration out of the box, which came as a surprise. Nevertheless, even though I thought about it, I will most likely not use the audio function much as it means getting a 2,5/3,5mm adaptor, and the interface for music is... well, it is not broken, but it is definitely not an iPod.
I'd say if you do not mind the hassle too much, get two devices, each according to your needs. Otherwise you will end up compromising on some end. That's why I did not get an iPhone for instance, too much compromise on the phone part for my taste.