Mobile devices have some inherent security challenges. They are typically designed with convenience, rather than security, as their primary focus. Apple’s recent revelation that it has found some Apps containing APIs that violate its standards is another reminder that mobile devices should not be used for information that needs to be secure.
For the details, see this article by Michael Mimoso on Threatpost.com.
Mobile devices are very convenient and should be used for all kinds of non-sensitive communications and data. But when you need to do banking or communicate truly secure information, stick with more secure tools.