Hi there
The DKU-5 is indeed a horrible expensive thing, costing the same as a brand-new unlocked 3315 here in Thailand.
But, using software such as PC-Suite, MobiMB or Oxygen, you can do a variety of things with it, such as:
-up/downloading pictures to use as wallpaper
-uploading colour operator logos
-uploading ringtones
-uploading games and applications
-synchronizing the phone with apps such as M$ Outlook
-backing up the entire phone
-managing the contacts and phone book
-using the phone as a modem
-sending SMS and MMS

etc etc etc
Is it worth the price? Definite "NO".

Kind regards....
Thanh