Pros: By default, noScript disables javascript, java, popups, flash and many other things that are annoying to people who just like to read text and view simple images. It keeps a list of websites with non-default properties for each of them, so that you can allow your bank, favorite websites, etc to have whatever properties you want available to them.
I was amazed when I first used this extension, how much of what I browsed did not even need javascript. When it does, noScript provides easy ways to enable what you need, either temporarily or permanently, by website. I find noScript eliminates 90% of the annoyances that intrusive websites try to deliver to your desktop, and it certainly prevents cross-site scripting and other potential risks when you visit an unknown website.
Cons: (1) If the website you are visiting wants to do something by scripting, and it doesn't announce the fact, noScript may be preventing something essential. (My domain signup here was probably delayed a day or two because I didn't realize the signup page was trying to popup a window.) (2) If you are in the middle of a form, press "Submit" and nothing happens, you must then carefully copy the material you have entered to the clipboard or another safe place before enabling scripts. Enabling them often results in a reload of the page and possible loss of what has been filled in. It is worth noting here that many (cgi) scripts DO function properly without javascript. (3) New versions of noScript come out about weekly these days. Be prepared to put up with reminders to upgrade relatively frequently.
I am fully aware of both the pros & cons, and would not be caught in Firefox without noScript!




