Not long ago when my previous Samsung phone died (I think I dropped it on its face one too many times), I upgraded to a Nokia 6133 with Bluetooth, MP3/WMA playback, and tons of other trimmings. I'd actually planned to use it as a replacement for my now-dead music player, but I've run into so many stupid little limitations that I have to wonder if I'm just being too finicky for my own good or if this really is just bad engineering.
The Nokia Pop-Port. No, you can't plug in your own headset. No, there is no micro-USB jack like, oh, almost every other major phone out there. Instead there's this proprietary connector which I can barely get any accessories for at either Radio Shanty or Worst Buy.
They did include headphones and a hands-free mike with the phone, but they're awkward and intensely uncomfortable to wear. I have my own cushion-plug headphones, but I can't use them.
I finally broke down and bought a connector to use my own headphones with the Pop-Port. It cost $15 and broke after two months. Part of that was because I had to disconnect it from the handset every time I wanted to get access to the memory card — or whenever the phone insisted I had to disconnect the wired accessory before doing something stupidly trivial (like sending Bluetooth audio somewhere).
The music player doesn't support playlists of any kind. It plays files in a folder in the order in which they were created. I have a workaround for this, but again, it's idiotic that something which has been a staple of digital music devices for nigh on a decade now is still not supported in a good many places.
I'd love to have a phone that can double as a music player and not kill my wallet, but at this rate I see myself sticking with my legacy MiniDisc player until the ribbon cable to the laser head finally develops an internal short (the cause of death for many of those devices).
... But other than all that, it's actually a pretty good phone.