Q:

Is 4K monitor a good replacement for Retina display?

I'm in the middle of reviewing different monitor options to finally buy one for myself. Please do not consider this post as a product placement. I'm not going to promote any particular brand(s), nonetheless I will paste a link to a particular one I found.
Basically as a MBP user, I fell in love in Retina display but I won't buy Apple Thunderbolt Display (27-inch) because I find this one as overpriced. I'm looking for something that will be as close as possible to Retina. Are 4K monitors good replacements?
I found one from Kogan (Kogan 28" 4K LED Monitor (Ultra HD)). Is it worth considering? Kogan was suggested by my workmate (we both develop software) who ordered one for his daily work. Not exactly this model but quite similar.
Can you share your thoughts or some recommendations?

A:

A 13" Retina MacBook Pro has a screen resolution of 2,560 × 1,600, while the 15" has a 2,880 × 1,800 resolution. 4K is defined as a 4096 x 2160 resolution.
So depending on how big the monitor is, a 4K monitor should actually look better from the same viewing distance.
As for my personal recommendation, anything but a Samsung.

