For those of you who have never met a Sport here's my take. It's sturdier than the Zip. The clip is a bit larger. The display is a bit less sharp, less color. The buttons that failed on my Zip are the same. There is no top or side power button. No clock or date.
Since there is no Rockbox for it, and may never be, here's a stock firmware review in brief. It's not as nice as the stock Zip firmware. Feels clunky. Clearly the CPU is very busy and button pushes aren't obeyed chop-chop. The button layout isn't as logical as the Zip. The center button is also the power button (Push twice.) so that can be an issue. The battery is smaller than the Zip but lasts much longer. Replaygain is busted on FLAC higher rez files. The player has no Bass or Treb but it does have a 5 band EQ. I click the low end up two ticks and the high end up one myself but that's earbud related. 2000 song limit. What's it sound like compared to an RB'd Zip? Not quite as crisp. Not as linear. A bit warmer. A bit wider soundstage. Listenable, but I'd rather have my RB'd Zip back.