As a guy who's been shooting the STW continuously since 92 I can say if I didn't love it, I wouldn't still shoot it.
Let's face it, it's been declared obsolete and/or dead at least four times since it first hit the market making finding factory ammo and brass difficult at best with any consistency.
It's worth it.
If I were starting out all over again today I'd probably go with the 7mm-375 Ruger but I've saved up a lifetime of brass so I really don't have to worry about ever running out especially since I have a half dozen other magnum rounds I can shoot as well as the 6.5's.
I've killed game all over N. America and Africa with it and it hasn't failed me yet so the STW's in my safe are not likely to be replaced anytime soon.