I'll assume that you meant Kenneth Branagh's "Mary Shelley's Frankenstein" rather then Richard.
Okay you should start by writing down the differences between the two versions
I'll get you started
a) the ending was changed, he makes his dead wife Elizabeth into another monster and fails horribly AGAIN
- what does this suggest
b) the movie paints Victor's only flaw in neglecting the monster, while in the book its not only neglect but embarrassment, he refuses to save Justine when he has a chance to etc.
c) what is his motive for creating the monster, the book presents multiple reasons why he might have done so while the movie presents only one sole reason why
d)his profession changes
etc. etc.
analyse what these plot changes do to the movie, the ideas, themes, characters, messages, mood
Now analyse WHY these might have been changed
ie is it the social context
are these themes still relevant
is it to make a more one sided fight
etc. etc.
there's more then enough to deal with here.