Hmm...

I think the interface is easy and straightforward. Keep in mind, though, I have never played with any other MP3 portables (except the S50, and only briefly there). I am told that it is similar to the Riot - people who know better, please correct me on that.

As to ease of use, I like it. It has a lot of power user functions, but there are also simple routines (play everything, etc.) for those less willing to tinker.