The link below is my first impression for the Mk1 (version 1):
The second version (mk2), which comes in more color (Red and Blue are now available, I chose blue), the button changed to a softer gel, and the time to switch on/off the player has significantly reduced.
Sound quality wise is still the same for Mk2. It's ideal for hifi recordings (clean music reproduction) and not so ideal for casual (fun, with certain coloring) use due to the constrain of features available in conventional players, such as the features of bass boosting, EQ, and etc.
To me, in my region, a sub $100 player is limited to several choice only. Commonly casual users go for iPod (with a little more topup), Sony players (more features, but to me, the interior amplifier is not powerful enough), or Sansa series (more audiophiles choose them because of the Rockbox feature) Therefore, Hippo Biscuit fills the void for the "Budget" Audiophile market segment.