Overall, do you think MLK jr's "I have a dream speech" was a success or failure?

It started out to be a success, but has recently turned into a failure. This is because the "woke" crowd thinks skin color is more important than any other qualification that a person may have. (Which is completely against Dr. King's message.)

Democrats will never fully embrace Dr. King or his message. Because many (not all), of the virtues Dr. King espoused were Biblical in origin. So that one fact alone puts modern Democrats at odds with Dr. King. I believe it was a success. Modern day Democrats think otherwise.

Success, it is more universally known than the Abe Lincoln speech. 

It was a resounding success. That's why it's still replayed, commemorated, and cited to this day. Expressing an ideal that has yet to be attained or may never be attained is not a failure, especially when it remains striven for, for if you find it not yet being attained makes it a failure, you must also find Jesus' "Sermon on the Mount" a failure, Bum, and every lofty speech ever given a failure, Bum.

It was a success, because it was the impetus for the Civil Rights Act and the ending of a century of Southern Democrat institutional racism.

Sadly, today his believe in a color-blind society is considered by the left to be "racist".  The mind reels.

It was a magnificent success.

It's such a pity that today's Democrats/Liberals ignore it.  They judge people by the color of their skin, not the content of their character.  They are also now pro-segregation at times.  I've linked to one of many examples of this from Columbia University. Even as they deny it, they admit they are indeed holding different ceremonies for different groups.

Democrats are once again embracing "separate but equal."

Didn’t work for Democrats, as they divide the nation by skin color in everything they do

I think the I Have a Dream speech was MLK's biggest success.  It's one of the best-remembered speeches of the 20th century.  It set the tone for the Civil Rights era, in fact it was kind of a turning point.

The speech was a success.  The results are still in progress.