Well (and we have diverged so far from the belgariad
)
I thought that they got some good senior actors into the film - Brom (?) we well cast - but they messed it up with poor younger actors. And in the end it was a quick film production for the christmas slot which had no potter or lord of the rings film in it. Thus bits were cut - and recreating the volcano - well that would have required nearly all CGI to accomplish - and could have been done, but it would have taken them too long.
However, they know that they failed, because after the cheap ending there is no sound of another film - and they would be hardpressed to make one since they changed so much