In most respects the Dell Axim X50 is a very good product. Bright, clear screen; lightweight; stylish; adequate built-in memory; two expansion slots to give you the option of using either SD or CF cards. The one drawback is that the firmware has serious issues with DRM (digital rights management) music files, such as the ones you can download from online music sites like Musicmatch.
Now, you might assume (as I did) that since Dell and Musicmatch have partnered, the Musicmatch downloads would be playable on a Dell PDA. You would be wrong. Sometimes the downloads will play, other times they won't - I have no idea why, but it has something to do with the Axim's inability to recognize the licenses attached to the music files. Musicmatch has no firmware upgrade for the Axim and offers no support. From what I understand, other customers have encountered similar problems with other download services.
Bottom line: For most functions, the X50 is great. For rights-protected music, look elsewhere (or at least be sure the Axim will work with the service you use).