I bought these and they are fab. They don't fit in the DS stylus slot however as I keep my DS in a carry case that isn't a problem for me. They actually measure 14cm long by 1.7cm at widest point.
I've lost & then found the standard stylus more times than I care to remember and I don't have that problem with this new one!!
Pro's: Great for playing your DS in the dark (under the duvet hehehe), easy to hold, novelty light-up (you have to make the whoooom noise yourself, sorry), hard to lose.
Con's: bulkier than a standard stylus