The Wacom Cintiq Pro 27 is the best pen display ever made. With a price of $3500 it is also the most expensive pen display ever made.
This Cintiq is an excellent device - except for the irritating fan noise. I love drawing with it. Drawing experience is excellent. But only incrementally and subtly better than previous models.
For creative professionals - who deeply care about color this may be a worthwhile and useful purchase that replaces the need to buy a pen display and a reference monitor
For everyone else - especially if you don't have professional color requirements, the value you get may not justify the cost.
This was a personal purchase.