That's not exactly a good reason to upgrade by itself.
It could be if you were required by some regulation to use a UNIX certified OS. IIRC, there were little feature changes that warranted the certification.
As for myself, I have an older iMac that won't run SL, a netbook that runs Linux and I am perfectly happy with both.
http://www.opengroup.org/openbrand/register/brand3555.htm