I don't think he'd be a bad manager for us; I think he's a sensible option who almost guarantees that he'll keep us steady.
It's just not an appointment that would excite me. I don't think he's a manager that would take us past, say, sixth and I don't think he's a manager who'll win us a trophy. If there's a chance we could attract Emery or Pellegrini I'd be much happier with that than apparently more than doubling Koeman's contract just to entice him here.
And on a more ridiculous note, my gut instinct is not to trust the guy.