It has exceeded my expectations, which is mostly coincidental due to the iPhoto app coming out at about the same time.
Since the original iPad, I only used my computers for a handful of things: Photo editing, video editing and conversion and music--and long web browsing sessions because the screen on the iPad 1 & 2 was low resolution. I'd literally get a headache if I read on it too long.
With the new model, I no longer have the headache issue. Text is crisp and perfect. Unless I'm at my desktop doing something else, I use the iPad for all of my web browsing, email and social tasks. It's better at them.
As for photos, the iOS iPhoto app (despite it's quirks) is much better than its Mac counterpart for editing. The retina display is amazing, the tools are easy to use and people seem to love the journals I make with it. I still use iPhoto on the Mac to store and organize my pictures, but almost all editing is done on the iPad now. I just can't go back to a regular monitor after using the retina display. Unless I need to do major surgery on a picture, or add custom text, I have no desire to go back.
My computers have officially been relegated to being "Trucks". Used only for heavy lifting. This may change when a retina display is released for the Mac, but the convenience of the iPad will still probably make it my go to device.
The only disappointment I have is number of developers who aren't updating their apps for the retina display or the A5X graphics. I know it will come in time, but it's frustrating. There are some great photo applications out there that haven't done it yet, so the pictures don't look good while working and the output sizes are limited--which is a big problem for professional work.