It is recommeded to do the updates once in a while and you also should do so. But upgrading OS X I don't recommend it since it will turn your mac slow. Self experience!
I have a four and a half year old MacBook Pro running on OS X 10.6.8 - the OS it was shipped with. I recently noticed I wasn't getting any updates and realised Apple stops sending them out after 3 years. I use my computer for research work that means accessing university websites, internet, and lots of word processing in Office 2011.
I do most work on Chrome and Firefox with Safari reserved for occasional use. However, when I try to login into my university server I get an alert message about the OS being outdated. I also regularly use my computer for online banking and now I am unsure if it is a good idea to do this and other such activities on an "outdated" OS?
I am starting to wonder if there are any security implications that I need to be aware of? Do you think I need to upgrade to a newer version asap? If yes, which one?