My very first scantenna broke within a year, and I bought another one after that but it also fell apart after about 6 months.
It could have been due to the extreme heat (110F+ in summer), but I would have thought their new "Heavy Duty" material would withstand more.
When it is actually intact it works very well.
The scantenna was a good choice for me because I listen to more than just airband (it is a multi-band antenna), but if you only listen to airband then the discone would be a better choice. The discone Dave suggested is specifically designed for airband so that would be a good choice.
From what I've heard about that RadioShack discone, it is made of rather flimsy material and falls apart quite easily. Perhaps someone who owns one can chip in their opinion on it.