The two side-by-side photos below, have the Samsung SP-A600 projector on the left, and the more expensive Epson Home Cinema 6500UB (best black levels of any under $3500 street priced projectors) on the right. In the second image you can easily see the darker starfield on the Epson, and if you look in the letterbox areas at top and bottom, you can also see the black level difference there. It is rather significant.
While I may refer to the black level performance of the SP-A600 as entry level, it is comparable to most, far more expensive projectors of just a few years ago.
Even with that in mind, for those of us who really appreciate the deep blacks of the more expensive "ultra-high contrast" 1080p projectors, its a significant, and important difference.
The image immediately below is from The Dark Knight. I've intentionally overexposed it to make a point. This is the type of scene where the difference in black level performance makes a huge difference. Because the outside areas of the scene, and for that matter the men's jackets are pretty black, with little detail at all, projectors with just "good" black levels look very flat - I've achieved that effect here. The SP-A600 comes up short in this image (say compared to the recently reviewed Sharp XV-Z15000. Even the Sharp, with its deeper blacks can't match the even more expensive JVC RS10 and especially the not the RS20 with its stunningly black blacks. The Epson Home Cinema 6500UB, is definitely a dramatic step up in black levels and Because the bright area of the image is of moderate brightness, projectors like the Sharp or the Epson, can't even get to their blackest blacks, whereas the JVCs, which do incredible blacks without an iris, would look drastically better.