LotusEater79

delete

sauce07

Armageddon - First half is alot of fun, second half is just one forgettable action scene after another.

slymer

Jeepers Creepers

DarthVong

Full Metal Jacket. First half.

RZ Halloween. First Half.

Rockmjd23

Grindhouse

Rammsteinfan

From Dusk Till Dawn. Like the film but enjoy the first half before the vampires show up. Once that happens its pretty bland.

DeanoBKN

From Dusk Till Dawn was what I was thinking of too.

The Bus

There's a ton of movies like this.

Most recently, I Am Legend. Once the "vampires" show up, it's... not good.

dugan

O. Things fall into place really well by the second half, but the set-up in the first half is sloppy.

tommyp007

Full Metal Jacket 1st half
Malcolm X Second half

Chad

Dreamcatcher

Michael Corvin

From Dusk Til Dawn is the best answer.

First half -
Second half -

Barings

I third this.

Norm de Plume

The best example I can think of a movie with two halves of wildly divergent quality is Mute Witness. It has a fantastic, scary first act before veering off into obnoxious comedy and espionage claptrap in the second.

BullGooseLoony

The League of Extraordinary Gentlemen - The first half sets up the story and this new world so well, and then turns into an f/x-laden, chaotic action movie with a really weak climax.

wendersfan

Fight Club. Once Project Mayhem becomes the focus it starts to fall apart. After "the reveal" it's pretty much unwatchable. Sad, because the first half of the movie is really funny and compelling.

dhmac

E.T.: The Extra-Terrestrial

The first half or so is quite good and deserving of a lot of the praise that the movie gets.

The second half (from the Halloween night sequence and onward) is not-so-good, full of mawkishly manipulative tearjerker scenes and silly chases.

.

GoldenJCJ

Just what I was coming in to post. You pretty much nailed it with your explanation.

Ace Of Spades

Both Fight Club and From Dusk Til Dawn are great answers for me, too. For the same reasons, too.

NEUMANN

Pearl Harbor,first half sucks but the second half is a great war pic.When ever i watch it i start it at the start of the Pearl Harbor attack then watch it through the Dolittle raid,makes a great 90 minute war movie

devilshalo

I was about to say the same thing, then I realized that it's really the middle of the movie that I liked of the actual bombing. I could do without the tacked on ending.

Doughboy

From Dusk Til Dawn - First half

Wedding Crashers - First half

Full Metal Jacket - First half

Superman: The Movie - I love the whole movie, but the first half is superior to the Metropolis part.

The Insider - Again, I love the entire movie, but the Russell Crowe first half is superior to the Al Pacino second half.

Mondo Kane

Lawrence of Arabia-Nothing seems to happen with an hour left.

mndtrp

From Dusk Til Dawn - First half
The Descent - First half. I didn't care for it once the creatures showed up.

Aphex Twin

Signs
The Happening
War of the Worlds (Cruise)