PhDs tend to have strange ideas about why people should give them money and no concept whatsoever of what deadlines or contractual obligations are. Other than that, they're usually pretty smart and well socialized.
If you hire one you have to keep it on a short leash and dole out the money as work is completed. Never, never, never, really never, like never squared, give a PhD project money upfront. They'll piss it away on computers and conference attendance and come back for more while trying to get a grad student or undergrad class to do the actual work.