The thing is, that apps may need to be reinstalled or in some cases upgraded. Not much new to write here but changing the OS has always meant we can't count on the apps surviving. Keep your install media/app/keys handy.
I have a mid-2010 Macbook Pro running Snow Leopard that meets all the specs for the Yosemite upgrade.
I know when I upgrade to Snow Leopard that many of my oft-used apps will no longer work, resulting in $$ to upgrade those programs, e.g. Microsoft Office, Photoshop Elements and a few others. However, those apps will run or have a work-around on Mavericks. In addition, I have read the howling about Yosemite slowing computers to a crawl.
I see in the Downloads section of CNET that Mavericks is available as a download, although it is not offered in the Mac App Store.
Would it be wise to upgrade to Mavericks via the CNET download?