[chii]

The only "downside" is that the format is an open spec, which allows anyone to modify the contents without going through the specific application. And it's only a downside if you are using the format as an obfuscation to prevent third-party compatibility/reverse engineering, or to lock in customers.

[crazygringo]

Yup. You can strip headers from the file though and keep them in your application though, to keep the file from being easily usable. And/or encrypt it.

[nly]

SQLCipher + a hard-coded or generated key in your app.