My experience with the Ipad2/3G is that the GPS inside it is crap.
Also the unit is near-useless for continuous in-flight navigation because you only have to accidentally touch the touch screen (which cannot be disabled, short of jailbreaking the unit and having a custom prog written which throws away the touch screen event messages) and the damn thing goes away to do something you were not expecting.
Also the Ipad is too big to yoke mount (in most planes) without blanking out something important behind it.
I would get a dedicated aviation GPS, but the bigger ones (e.g. the 695) are still too big to yoke mount in most cases IMHO.