I just tried this with my Creative Zen and to be honest, the biggest drawback I found is that it lost my transfer list.
I spent like an hour working out all the albums I wanted to put onto it (which was extremely easy to do by the way) and then hit transfer or whatever, and it came up with a box saying something about duplicates did I want to continue, so I said yes, then it said some files had errors or something, so I clicked ok or whatever it was. I cant remember exactly.
Anyway, then it went back to the program, and it had reset the list of files I had lined up to transfer.
I just lost an hours worth of work.
I dont know if its a bug or by design or whatever, but after I, or anyone else for that matter, spends all that time making a big list of files to transfer to my mp3 player, the program should never, under any circumstances in my opinion, take it upon itself to wipe off that list and get rid of it. I just lost an hour of my time and a lot of effort.
If it wants to get rid of my list at the very least it needs to ask me so I can say no, but to be honest, I dont see why I would ever want a program to get rid of and clear a list I just spent hours making unless I tell it I want it to get rid of it.
Sorry for sounding a bit harsh but I just lost over an hour of my weekend and hopefully this can be taken constructively to improve/fix this feature/bug.
Also, to top it off, the transfer started slowing down after around 180 files, then basically just hung there and didn't continue so I went back to Notmad Explorer which transfered all 3800 perfectly in one go with no hitches.
One final other point while I'm here, I also had problems with Notmad Explorer while I had your software open. After a bit of experimentation I found that while your software is open, it automatically connects to my zen and I couldn't see any way to disconnect it or to tell your software to just leave my zen alone. With Notmad theres an option to 'connect' or 'disconnect'. In the end I had to kill your program just so that I could let Notmad connect which was a bit annoying as it meant I couldn't use it to listen to music in. It also means that my Zen stays powered on while connected to the computer and in USB mode and I cant use it normally because it is always in 'talking to pc' mode so I cant use it as a player.