This is my newly bought iPad2 speaking
To be honest, I do notice the resolution difference when I'm browsing the forums here, where the fonts are really small. But it's one of the few cases. I won't notice it in most apps.
Retina display is reall not necessary, considering the sacrifices. Maybe I won't hate it when Apple brings iPad4, when other tech factors are more mature and balanced. For the iPad3? Retina display is a monster.
Though some of my reasons are kidding, the nail hemmering one is the charging time. I doubt whether anyone can bear it...
After all, I'm happy with my iPad2