Cheap and inconvenient.

The problems with Wal-Mart's music store.

Carl Howe at Blackfriar's Marketing points out the problems with Wal-Mart's supposed bid to unseat iTunes.

The result: customers are likely to cherry-pick low-cost tracks at Wal-Mart when they can, but any large-scale defections from iTunes or even Amazon just aren't going to happen without a lot more marketing work.

Howe notes that Wal-Mart has a thinner selection and requires Windows Media to even browse its collection but he doesn't mention the biggest problem, possibly just because it's so obvious.

It's just not a convenient way to get songs onto your iPod.

As Michael Gartenberg says:

Devices still drive folks to the stores and not the other way around.