The title may be a bit confusing. See the below example:
The movie (was/is) so good.
The simplest guideline on deciding which tense to use, past tense or present tense, to describe an object comes down to whether the description was only true that that time or is true even to the present point of time.
But now we talking about literary work(movies,books,etc) of which quality tend to stay the same over time, which tense should we use?