This may be a long one, but here goes...
First up, I saw the Amazon review for 3.5 stars, and noticed the "what customers also looked at" links and saw the 'Discovery Kids' model which looks exactly the same but with slightly higher review ratings. All the specs match; are we seeing one vendor with two brand names slapped on?
Anyway, I'm the proud papa of a 1.5-year old, and he loves, loves, loves music. We tried dedicating an iPod with speakers to him, putting it on a high shelf, but since he'd try his darndest to climb up and get it (he's quite persistent), I found a solution: The Fischer-Price Kid Tough Music Player. Now, it's also got 256 megs of memory, which might seem piddly, but when you're anywhere between 1 and 5 (my kid has cousins who like to 'share' his music), that's more than enough. External speakers were nice, too, since (1) our toddler would yank off any headphones, (2) he can have music on while he plays and (3) he doesn't damage his hearing. The FP model does have a microphone, but that's really not necessary. The FP also uses C batteries, but they last for weeks at a go thus far.
I guess what I'm getting at is that this kind of player is great for kids who are still rough on things and who like to carry their musical toys around. The reliability seems to be the biggest issue, but for 20 bucks, I'd say it's worth the risk.
Edit: Fixed my links. Forgot I didn't need quotes. D'oh!