Can I ask what you use it for? Thinking about this but worried about sharpness and colour, I'm a designer and love the idea of having lots of windows open. How is the colour and does the curve worry you at all?
Safari, Mail, Photos, and Web Design... Mainly.
It is not very sharp... Very low PPI. I'm going with two 5K's. Once your eyes see the iMac 5K, it is difficult to use anything with less PPI.
The color is pretty accurate... Doesn't seem that bright overall. The curve is nice. If it was brighter and had a higher PPI, I'd definitely keep it!