Overrated. It might be a bit nice to have but not necessary at all. If you are familiar with the transition from iOS pre-retina display, to retina display support in iPhone4, there was a lot of pixelated looking icons and UI elements before developers updated their apps to support the retina display. The web experience is going to be somewhat similar, and I don't think many web developers are on board with developing ultra high resolution versions of their websites for a niche group of people using retina displays at desktop resolutions (at least not any time soon).
As a side note, Apple has fortunately packed in a lot of display settings, so you don't have to view everything at retina density (meaning: you could view content/websites at a normal resolution).

Anyways, not worth it IMO. I generally like Apple products, have a ton of them, but if there is one thing I won't do and that is being an early adaptor of their products. My wife is the opposite has encountered so many issues. I recall my wife returning 3 iMacs when she bought the first gen of the last design update.