I picked one up. Currently, I have The Black Heart & the 126 dodge rating / armor on use trinket from Heroic 10 man Trial of the Crusader. My guild had really bad luck with tanking trinkets -- only 1 Heart of Iron and 1 of the 155 stam + parry trinkets from 10 man.
I won't use the 170 stam trinket in most fights, I have 36.5k unbuffed health right now. However, it'll be nice to have something to swap to for magic damage fights, where something like the dodge+armor trinket are useless.
Heart of iron on use is horrible. Its going to make you miss 1 attack every 4 minutes (every other click) when solo tanking. Black heart and glyph of indom are better in some situations though.
If you are wearing a stamina trinket, you want the most stamina you can get and can safely ignore any proc that does not reliably increase your effective health when you need it most (impales, dreadscale enraged burning bite, etc)