I think the man deserves a memorial...but I think he deserved a better one than this. There is something unnecessarily cold and forbidding about this, especially with the body language and facial expression. That's not the impression I've ever gotten from his writing and speeches; he seemed like a more welcoming individual than that.
I think perhaps they were trying to incorporate the concept of the strength inherent in passive resistance (such as with sit-ins and so on), but failed in their objectives.
I think that had I been doing this, I would've opted for something more relatable. Ironically, the model I have in mind was controversial in its own time, but what I imagined a Martin Luther King, Jr. memorial to be before I saw this was a bit more like the statue of the Vietnam soldiers that is next to the Wall. Something that seems more like a picture from a march, that seems more in media res, where you can read the combination of hope and anxiety that I'm sure people were feeling in those days. A snapshot from history, in other words. I think that might have embodied the objective of showing that race relations are still a work in progress that they might've been going for here.
But I think showing him, and perhaps some others with him (perhaps family members who joined him?), like a shot out of a history book, would've been much more engaging and more true to what he did.