Do you mean banking over the phone or banking over the mobile web?

Either way, I feel pretty comfortable personally, just because my bank protects me against fraud and identity theft, and honestly there’s not much to steal.

But if I had anything super important to do, I would always do it in person.

mobile internet – no
internet on laptop when mobile – depends in hot spot and area but probably no (not just because of the usual internet security crap but also shoulder surfers etc)
checking balance by text – would feel secure but would probably check at ATM instead
banking over the phone – i never bother with it

Also my finances are set up so I don’t need to keep checking them that often (it helps when you don’t actually have any money to manage)