Ever since I switched to my 2015 13" rMBP, I've really enjoyed using it for the retina display. There is such a stark contrast between it and other high dpi displays in terms of colour fidelity and image representation thanks to the almost impossible to see pixel pitch. This is most apparent when going back to non high dpi displays such as the 1080p external monitor I hook it up to sometimes. The display quality is like night and day. It pains me to look at the external display now and I only use it when I really need the extra physical screen space. It really makes me want to get the 5K iMac but I really can't justify it.