I think it looks good, but why did they use white stone?
Because the stones chosen for monuments have nothing to do with skin color and it would be incredibly tasteless and against what MLK stood for to give him dark-colored stone just because he's black? It's making the entire focus "on the color of his skin instead of the content of his character."
As for the whole "Martin Luther King as a conservative" arguement, here's a link to an opinion piece from the (yes, staunchly conservative) Heritage Foundation on that matter. I thought it made some interesting, if arguable points.
Heritage site
"Interesting" is certainly one way to describe it. Ignorant and offensive tripe is a more apt description, however.
It proceeds from the oft-quoted but false premise that faith is the exclusive province of conservatives, and that morality can in turn only come from faith. I'm sure this comes as a surprise to the millions of deeply religious black Democrats in America who the author rather ironically (given the subject matter) just alienated. Most liberals in America --regardless of color-- are religious, contrary to the usual conservative talking points. Additionally, the ridiculous fearmongering idea that people lacking in religious affiliation or belief in a deity are incapable of having a strong moral code is so laughably out of touch with reality it's not worth dignifying any further.
Also, I'm pretty sure MLK's message was not to that cultural diversity divides us and should be eliminated, but rather than one should have equal rights and not be judged based on that diversity but instead the content of their character, which is an entirely different thing from saying diversity is a problem that's holding us back as the article suggests. So, not only does the author insult the very people MLK was fighting for equal rights for, she misunderstands his message completely while appropriating it for her own petty political aims.
As far as the monument itself goes, I don't find it to be a travesty, just kind of bland as others have said and with a bit of an odd, passive and restrictive pose. I would have gone with something a little more dynamic like him waving or pointing out at the crowd while shouting a speech, such as in this picture from his speech in Atlanta:
I also might have incorporated this quote of his...
"Everything that we see is a shadow cast by that which we do not see."
...by perhaps having the statue cast a shadow over the main entrances to the memorial, thus making everyone who enters first stand in his shadow (depending on the time of day obviously), both to symbolize that there is still work to be done by you the visitor, and to express that for every action he took there were countless other acts of bravery and civil disobedience unrecorded by history that contributed to achieving civil rights victories.
Other than that though, the location is perfect: triangulated between the Lincoln, Jefferson, and Washington Memorials/Monuments, thus replicating the location of his I Have a Dream speech as closely as possible, while also referencing Lincoln (cited directly in the speech), Jefferson (the Declaration of Independence was cited), and Washington (who presided over the writing of the Constitution, which is also cited in the speech).
Here are some more images for anyone who's interested:
