I've been using a Pogo Sketch for over a week now with my iPad.
It's nice and does work as it states and also as I have seen in YouTube videos.
The only thing I wished they had included with the stylus was a cap to protect the drawing tip. It is a soft material (same anti static material used to house IC's and Transistors when shipped).
I was so excited waiting for mine, that I couldn't wait any longer and made my own to test with. I used an old telescopic radio antenna and inserted in the open end some of that material (anti static) and it work quite well, but not as well as the actual Pogo Sketch.
I've done some line art as well as caricatures on the iPad since then using Sketchbook Pro.
Some of you will want that glove you heard about, it will certainly reduce the accidental taps and scrapes your palm will make.
Other than that, its an excellent drawing surface on the iPad and will induce a sort of glide effect to your drawings, as compared to paper that has the feel of drag and to some is easier for blending. But with the right practice the iPad makes a great drawing surface and blending just comes easier each time.
If you haven't used many electronic/computer aided drawing programs, its a steep learning curve other than your natural ability to compose, but the controls and tools in the software can be daunting at times to discover and learn to incorporate into your technique.
Again, this depends on the software and I find SketchBook Pro to be a nice addition to my iPad especially with the Pogo Sketch to go along with,
Now to just find an appropriate cap to protect the tip when not using it.
It does have a clip to use for a pocket or small bag, but the tip is still exposed and gathers lint and dust like you wouldn't believe.
I liked mine enough to order a few new replacements or spares.