I agree with those that said the difference in megapixel count doesn't amount to much. Case in point, compare the Epic 4G (5 MP) camera to the Evo 4G (8 MP) camera.
Prior to actually purchasing an Evo 3D I pretty much felt that the 3D was gimmicky at best, but now that I've owned the device for about 6 weeks now, I feel that it's not a gimmick, BUT there is limited usefulness of the 3D feature.
I would have to compare the 2D picture quality from the two and determine whether or not I could see an improvement in the 4G+'s picture quality. As it stands now, I don't think there would be that big of a difference. I imagine this 4G+ to be an Evo 3D with the Evo 4G's camera, and while there are perceivable differences, it's not so much so that it's a game-changer, so to speak.
So, to answer the OP's question, I agree with those that said the Evo 3D represents everything the 4G+ is/does PLUS adds 3D capability to the phone. It's one extra feature.