Pentile is great engineering. Given the choice I'd have a pentile display with the same number of sub-pixels over the alternative any day. If it was the same number of pixels, I'd maybe swing the other way but generally pentile has been a victim of the fanboy wars because (so far at least) Apple hasn't used it.
Though I believe it was rumoured (and frankly would have made engineering sense) for them to use it when they quadrupled the resolution in the iPhone 4 but Samsung couldn't guarantee enough production to fulfil Apple's expected demand. I can easily imagine another world where Apple makes some slick videos explaining the benefits of Pentile and anyone who doesn't have it is mocked, similar to how the iPhone's Retina Display, which they admit in the very name goes beyond the point of visibility in normal use is considered the minimum benchmark for a good screen.
Pentile may be great engineering but the colors it shows are not true, and it has significant banding across solid colors. As an interface designer, it makes my eyes bleed and my graphics look sub-standard.
Are you talking AMOLED or pentile? AMOLED has a distinctive color-cast at low brightness and a color gamut that exceeds the standard which can make it look cartoony, but so do other screens e.g. the iPhones 3 and 4 which have too small a range and can look washed out as a result. The banding sounds like an AMOLED problem too (unless you mean the "stippling" type effect you can see if the pixels are big enough).
But neither of your complaints appears to be related to pentile vs RGB stripe. If you're talking about low pixel density then it's the same Mac OS vs Windows text rendering debate. There's not enough pixels so which kind of ugly do you prefer (or are you used to)? Some people like the hand wrangled pixels, other just let it fall where it lands. Things designed for one system will look worse on the other and especially bad to people who prefer the other look.
Though I believe it was rumoured (and frankly would have made engineering sense) for them to use it when they quadrupled the resolution in the iPhone 4 but Samsung couldn't guarantee enough production to fulfil Apple's expected demand. I can easily imagine another world where Apple makes some slick videos explaining the benefits of Pentile and anyone who doesn't have it is mocked, similar to how the iPhone's Retina Display, which they admit in the very name goes beyond the point of visibility in normal use is considered the minimum benchmark for a good screen.