When you turn the computer on for the first time what you are seeing is basically 1440x900. The only difference is that everything is sharper, since there is a greater pixel density. With Retina and resolution scaling, the physical screen resolution no longer necessarily equals the display resolution. So even though the screen is 2880x1800, the elements on screen are scaled to appear the same as the 1440x900 display on a standard MBP. You don't get any extra desktop space, unless you scale the resolution to the 1680x1050 or 1900x1200 equivalent.
There is no way the computer would be usable if it actually rendered everything at 2880x1800 native. Normal 12 point text would be illegible on a 15" screen.
I visited an apple store today. The retina display is simply beautiful. The workspace is suitable, however i can see it being a bit small. In 1440x900, the screen was super sharp. You simply have to see it for yourself. I even put it in 1920x1200 mode and it was still beautiful, but things might be a little bit too small for some. It looked better than any other MacBook pro. Also, the glare wasn't as bad as on other pros.