If I may indulge in some hyperbole, this thing has changed my life! It is the most amazing device for doing digital art on. It can be used like a sketchbook for scribbling out ideas, doing gesture drawings, and the like. It can be used as an animation desk, but without the need for paper, scanning, etc. It can be used like a painting canvas, without the need for cleaning brushes, smelly turpentine, messy paints and smocks. I'd used Wacom Intuos tablets before, but had difficulty using them and find using the Cintiq so much more natural and comfortable to my workflow.
I don't think a day has gone by since I bought it that I haven't used it in some way.
That's TVPaint Pro 10 on the screen, my favoritest animation application, and I think the only commercial 2D application available for Linux. The surface of the monitor is the entire drawing area. It's ideal for working in high-definition resolution; and in fact, I have taken to working at 2K resolution, which is film resolution (2048×1080).
While applications like GIMP and MyPaint will always be in my set of tools, I have started using a new digital painting application that I find myself using more and more. It's an open source application, developed primarily on Linux, called Krita. Here's a screencap:
It's an application that is designed for digital painting, and its feature set lies inbetween the more general and complex photo retouching apps like GIMP and PhotoShop and the artist friendly easy-to-use apps like ArtRage or MyPaint. It also supports several color spaces like CMYK, in addition to RGB, and also has good built-in tools for color calibration. It is also becoming popular for comic artists. I guess in some ways it's similar to Corel Painter, although I find it far easier to use, and I found the performance of Painter to be rather poor, especially at higher resolutions. I believe Krita has some animation support coming down the pipeline, which could make for an even more interesting application.
The image above, BTW, is a piece of concept art for a hand-drawn animation short on which I have started pre-production work. But that is a topic for another post!