An adjective for a film or book with very long dialogues

The adjectival form of 'dialogue' (variant spelling is 'dialog') is

dialogic also dialogical, adj.
pertaining to or characterized by dialogue.

[dialogic. (n.d.) Random House Kernerman Webster’s College Dictionary. (2010). Retrieved January 25 2016 from http://www.thefreedictionary.com/dialogic ]

Thus, aside from technical senses of 'dialogic' ('dialogical' is a variant spelling), a dialogical novel, for example, is a novel dominated by dialogue, whether by weight or by volume.

An example from the wild, with reference to a novel:

Spanish novelist Delibes (The Hedge, Five Hours with Mario--a monologue) here uses a series of psychiatric interviews to make a spare, dialogical novel.

(From a review of "THE WARS OF OUR ANCESTORS By Miguel Delibes", in Kirkus Reviews, 1992.)

Another example, with reference to film:

Today's films of counter-information are distinguished by an extensive arsenal of stylistic devices: self-criticism, bluff, irony, wit, the view of events from the periphery, the letter form, dialogical film forms.

(From "Filmic Counter-Information: A Few Highlights from Film History", 2003, at the Republic Art site. By Thomas Tode, translated by Aileen Derieg.)

For extended and technical senses of 'dialogic', and an outstanding work generally, see The Dialogic Imagination, by Mikhail Bakhtin.

• Verbose/ Wordy

  using or containing more words that are needed (according to Oxford dictionary)

• Long-winded

  continuing for too long and therefore boring