It's a neat little device. I bought mine probably a year or so ago and it's sat largely un-used. I think they were fairly new when I got mine, so these issues might have been fixed, but...
1) small size (think mine's 7 inches or so?) 2) difficult/impossible to write small enough to fit a good amount 3) no way to save pages (in any way). I tried to hack my way around this by snapping pictures of full pages, but it just became too much of a hassle.
I see it as more of an appliance than a tablet, serving one purpose really well. It's like an etch-a-sketch for adults. I find that in programming I often need to scratch paper to track variables or do simple state diagrams and once I've solved the problem I no longer need the paper.
I haven't tried it IRL yet, but at that price, I think I will. Call it a kindle meets etch-a-sketch.
http://www.improvelectronics.com/us/en/boogie-board-LCD-writ...