Does anyone have one and how do you like it?  I was interested because I use only MOE grips on my ARs.

I like mine just fine.  If fits perfectly in my Magpul grip.  I basically bought a couple to put in some SHTF rifles as a "just in case" backup.  
To me, having carbon scraping tools, a front sight tool, and bits for tightening or removing Magpul rails is cheap insurance.  

The castle nut wrench is a nice extra feature.  With the short handle, you'd probably have to rig up some sort of cheater bar to actually break a castle nut loose.  But if you had one loosen up in the field, I'll bet it would work fine for snugging everything back up.