Mr Pig said:...My son's iMac screen simply wasn't a great screen. As soon as we took it out of the box I noticed that it wasn't as sharp as the Ilyama screen we had at the time, fine type was pixilated rather than being sharp, straight lines. I assumed it was maybe just a setting or something but it wasn't, it was simply not a very good screen.
Actually it probably was; OS X uses a different algorithm for smoothing fonts compared to Windows. Users familiar with Windows often find text - especially at smaller sizes - to be less sharp on OS X. Conversely, Mac users can complain of text on Windows looking stark and blocky. Depends what you're used to. You can very easily adjust the settings in System Preferences.