Well I finally got around to buying one from play-asia and I thought I'd give my review on it. The pictures will be linked to larger images if you want a closer up pic. I also don't normally review accessories so this was kindof awkward for me to write. So sorry if it comes off kindof weird. 
Any critique or questions are welcome.
Basic Rundown
A DS Lite stulus with an outer pen-like case that can work just as well on a normal, fat DS. However the Touch Pen will only clip on to the DS Lite and the two stylus included will also only fit into your DS Lite.
Contents
1x Touch Pen (Two Parts)
2x Extendable Plastic Stylus
2x Extendable Plastic Stylus
Summary
I had originally come across this a few weeks ago at the end of the recent Play-Asia sale. At the time I was thinking it would be good to have a large stylus for my fingers as the basic stylus is small and is difficult to use for for with certain games like Elite Beat Agents.
Upon recieving it, I was a little surprised that it wasn't a single item. Like the picture above it came with two extendable stylus and a two-piece touch pen which you put the touch pen. The stylus themselves are fairly cheap and easy to pull apart made completely of plastic and has a somewhat cheap feel. Near the top end of the stylus has a small hump that snaps into place in the upper half of the Touch Pen. From there it can be extended but I never personally found it worthwhile to extend it while in the Touch Pen itself. Especially since when you extend the stylus, it's an all or nothing thing and even then it doesn't push well onto the touch screen when extended.
After having snapped the stylus into place you have to do the same with the lower half of the Touch Pen. It snaps into the back side of the upper half of the Touch Pen fairly easily. Though on the Touch Pen I recieved it didn't stick in very well and may be a universal problem with the product. This caused me to lose the bottom half of the pen when playing Elite Beat Agents with it while extensively testing the product.
Once it's put together there is a thin rubber grip at the bottom that feels fairly decent and was quite confortable to me. I had no problem with any slipping after a few hours of play and my fingers didn't hurt through the entire session. Besides the rubber it has your basic pen clip at the top of the Touch Pen that can be clipped into any pocket if you're a person who does that sort of thing. The pen also includes two humps on its clip that can be stuck into the top of your DS Lite fairly securely. Though I do not believe it will stay stuck if you carry it in a bag or your pocket. It may work well in some cases but I don't have any so I am unable to say.
Conclusion
I think it's a fairly good product and will be using it on future games. It helped improve my play on Elite Beat Agents by quite a bit too. The only major problem I had was with the bottom half of the pen coming off when I was really getting into the most difficult mode of Elite Beat Agents. Though I found a remedy for that problem! No, it's not duct tape, I'm sorry. It's your other super-fixer-upper, Super Glue. I had glued the extendable stylus shut, then into the touch pen, and finally the top and bottom half of the touch pen after that. Since then it has worked great but unfortunetly I sneezed and got glue on parts I shouldn't of, so yeah. Don't sneeze.
Any critique or questions are welcome.