Downsides include a relatively pokey 200MHz core, poor battery life (though nothing BlackJack owners can't relate to, we reckon), and -- yeah, we're starting tonitpick here -- the lack of a mirror next to the camera.
The sheer momentum once again allows us to temporarily gloss over the plot issues at least until after the credits roll, although careful viewers will find much tonitpick as the film unspools (certain climactic develops severely undercut the potential for peril in any future installments).