He's referring to the screen door effect on SAMOLED phones from the pentile matrix screen. You don't need superhuman vision to see it. It also makes smaller text blurrier than the Evo text because of the way the subpixels are arranged.
I had my first chance to play with an Epic today. Had my Evo alongside to do some comparisons. Here were my major observations, with the disclaimer that I'm trying to be objective as possible, and I don't have any brand loyalties.
The Evo is brighter. I loaded google.com on both phones, making sure to turn on full brightness on both, and also full brightness on the Epic's browser. The Epic's white is very bluish, and this was noticeable on all 3 epics on display. In the dark range, the Epic was very good. Dark details lost on the Evo were still present on the Epic. The Epic's colors were more saturated.
These observations did not surprise me at all. OLED-based screens get their incredible contrast ratios because of their ability to produce almost pure black. It's like dividing by zero. You get an infinite result, so if you can keep your black value as close to zero as possible, you get a huge ratio value. I was a bit surprised to see the bluish hue on the Epic. Some might say I'm used to my Evo's "yellower" screen, so my eyes are "white balanced" to yellow, making the Epic's screen appear bluer. I really don't think this is the case. I'm pretty good with colors and can typically identify a true neutral gray/white.
The Pentile matrix screen of the Epic did bother me. It gave edges of text a jagged and fuzzy feel. It's only a problem with high-contrast edges (like text). For images and videos, it isn't noticeable at all. I would demand a much higher pixel density (resolution) for Pentile screens. Evo's screen feels much more crisp and sharp. I also think that anti-aliasing algorithms for fonts are optimized for traditional square pixels, which may further contribute to the fuzzy feel of the Epic's text rendering. The same effect can be acheived when you rotate text in Photoshop to some non-90-degree angle. The edges get a bit blurrier.
The 4 capacitive buttons on the Epic are annoying. When the backlight for the buttons goes out, they are completely invisible. I hope there's some way to address this on a software level, like keeping the backlight for the buttons on whenever the screen is on. Unlike others, I did not have any issues with the buttons being less responsive.
The camera on the Epic is INCREDIBLE. To me, this is what makes the Epic shine when compared to the Evo. Looking at the live display while in camera mode was like looking at the display of a dedicated digital camera. It was immediately clear that the optics of the Epic's camera were vastly superior to the Evo's. I took a few shots of the same thing under the same conditions, and there is no comparison. The Epic actually does a GOOD job under low lighting, and an AWESOME job with full light. I was simply blown away that such a good camera could exist on a cell phone. I also loved that there was a physical shutter button that acted like a traditional camera: half-press to focus; full press to shoot. Bravo.
Framerate on the Epic was impressive. Very smooth scrolling, unlike my stock Evo. I still can't believe HTC thinks that 30FPS is an acceptable tradeoff for HDMI. Touch tracking was very responsive, again, unlike my stock Evo. I'm glad both issues were fixable via rooting and a custom kernel, but come on, this type of quality should come out of the box. Especially if you want to be competitive with the iPhones. Anyhow, Epic's framerates are very good.
I was really hoping to be impressed by the physical keyboard, but it was so-so. The slider felt solid, which was good, but the keys themselves felt unsatisfying to push. Hard to explain. But it reminded me of old-school calculator buttons. A bit loose, and kind of mushy when pressed. I also didn't like the way the keys were arranged into a perfect grid. If you're going to provide a qwerty keyboard, you should stagger the rows accordingly. The grid arrangement made me press in-between keys way too much.
OTOH, Swype felt a lot snappier on the Epic than it does on my Evo. Not sure if this was a placebo effect or something, given that Swype was factory-bundled with the phone and therefore has probably undergone more quality control than my beta swype. But it felt more accurate.
There are a lot more features I wanted to test but didn't have the time. I'll be checking these out at a later date for sure.
I was really hoping to get my wife this phone to replace her iPhone 3G. While I think the Epic is definitely a better phone than the iPhone 3G, I wanted her first Android experience to be better than the Epic. I'll have her try it out anyway; maybe her impression will be different than mine. But after today, I'm a bit less enthusiastic about pushing the Epic on her.