I did the math. If you go by logical pixels, the GN has the most pixels on any smartphone ever. If you go by subpixels, it ties the iPhone 4 and 4S and still beats everything else. Also, it's quite a bit higher pixel density than any other android phone, and the higher the logical pixel density, the less the subpixel configuration is going to matter.
In fact, you could probably argue that at some point PenTile actually becomes preferable to RGB because it capitalizes more on the fact that human eyes are tuned more for luminance than chrominance. Your eyes don't actually NEED all the color information in every square nearly as much as they need the luminance information. Digital camera sensors have been capitalizing on this practically since they were invented. They don't even HAVE subpixels. A 12 megapixel camera has 6 million green pixels, and 3 million each of red and blue. They just alternated R G B G and then use interpolation to give every pixel a red green and blue value. There's even been a manufacturer that actually made "full color" sensors, but in the real world they aren't much of a gain and tend to have a much lower logical resolution so they end up coming out behind.
The problems with PenTile screens are that if the density is too low it starts to become noticable, and also if the software isn't accounting for the subpixel configuration when it anti-aliases text, that can also cause weird rainbow fringes. I'd be worried about that problem if it weren't for the fact that Google spent 15 minute hemming and hawing about their tighter hardware/os integration and fonts that are "optimized" for mobile screens.
Plus, I'm upgrading from a (non-Super) AMOLED Droid Incredible. That thing had a PenTile display and it didn't even have the benefit of a much higher logical pixel density than the competition to compensate for it. The Galaxy Nexus does, so I'm pretty sure it's gonna be fine.