I think it's undeniable they're useful. When I first got mine and started messing with it immediately a dozen past projects came to mind that would've been a breeze with it. The longer I own it the more I realize it's uses. Some guys say getting an OMT changed their whole workday. That wasn't the case for me. When I use it, which is only occasionally, it's awesome, but I can't think of a case where nothing else will do. I think only very rarely is it the best tool for the job, but tools that perform multiple functions sometimes aren't stellar at any of them.
I also think I may be under-utilizing it.