Overdrive typically won't damage a system, but it will give you a more unstable hotter system than you will achieve though bios overclocking. Overdrive typically sets the Vcore higher than it needs to be to hit the targeted overclock resulting in more heat production. That is a stability issue. You may not notice this issue while doing normal tasks or even video gaming (as most games are going more GPU intensive than CPU intensive) however when you go to do something like video editing, or any massively intensive CPU chore your going to have higher heat produced than is necessary. If Overdrive were 100% safe it wouldn't have a warning that you do it at your own risk and void your warranty once you use it. Its a good tool, but too vague in its coding and sets Vcore too high for lower overclocks.
Its far better for a noob to read over the guides (I posted a good one but there are other good ones out there too) get to know their bios, understand what changes they are making, make very small incremental changes and achieve the best overclock possible. Along the way that person knows how computers work a heck of a lot better too, at the end they will be an overclocker and not a noob. Using Overdrive at the end they are still a noob that doesn't understand what the program did. Its like arguing why go to school and learn for yourself when Google can give you the answer- take away Google and then what?
Believe me, no one at Overclock.net is going to boast about their Overdrive overclock nor recommend using Overdrive over bios overclocking.