<p>If you are a power user of Pages or Numbers, then when you update your OS to Mavericks you updates will appear for Pages, Numbers and Keynote. The main goal of these is to eliminate the kludgy transition between iOS file and Mac OS file - which required a translation of data and led to synch problems*. The solution is a single file structure, which is huge for the future and which makes synching easier and more reliable. The cost is they cut out a lot of power features from Pages and Numbers. </p>
<p>If you use things like Mail Merge - like for your business - then you should not open any document in the new version of Pages. The old version will still be on your Mac but once you open it in the new version the file will be translated into the new format. I don’t know of a way to reverse that. </p>
<p>My guess it will take a few years for all the features to reappear, some quickly and some slowly. Apple has done this before - iMovie, FCP, etc. - because when they need to simplify, they take the application to the ground and rebuild it. They added important features to FCP almost immediately because that’s an important client base. I have no idea what they’ll do with Pages and Numbers. </p>
<p>Mavericks otherwise is terrific - and this issue is with iWork, not the actual OS. I highly recommend it because it will add significantly to battery life. I suggest reading John Siracusa’s long review at Ars Technica of the battery savings/power management changes in the OS. (Much more readable and interesting than his obsessive dissection of tags.) </p>
<p>Another really neat feature is tabbed Finder, which means you can open a Finder window that has tabs so you can keep for example your downloads, applications, desktop and utility folders all open in one window. Since I also use Spaces - virtual desktops - this is a real bonus. They also continue to integrate the OS with iOS in useful ways.</p>