We're always telling our clients to update to the latest version of WordPress, and now 3.3 is here. Should you update?
It's a fairly major upgrade from WP, with much improved facilities if you're using an iPad and streamlining of the Dashboard area, with your submenus flying out at the side on mouseover, rather than expanding downwards (very useful if you use a laptop with a smaller screen). The media uploader has changed to a more simple drag and drop facility. Behind the scene there is improved javascript, which won't really affect you as a client. Find out all the changes here at the WordPress site.
Because it's a major upgrade, there are possibilities of bugs which need to be ironed out. Eager users will be finding those bugs and reporting them, so it may be an idea to wait until the next upgrade is released, which will probably be by the end of the year or early in 2012.
If you just can't wait to upgrade, we do recommend you back up your site before, in case there are any issues.
If you are unsure about backing up your site, WordPress has answers to your questions and a how-to here. If this all looks a bit too complicated you may like to try out Vaultpress, a plugin which backs up your site every time you make a change. It is not a free plugin - and there is a privacy issue in that your data is being backed up on Vaultpress' server - but worth the minimum $15/month.
Of course you can always ask us to perform the upgrade for you; we do that for our clients as a matter of course for smaller updates and will be waiting until 3.3.1 is released before we backup and upgrade your site for you, host server permitting.