I do not have any personal experience with cobuying land, but from the multiple accounts from others that did go that route that I have heard about...I wouldn't do it, no way, no how! Also, I know realtors that when they hear about a potential "partnership buy", they will avoid that deal because of the likely headaches and delays, etc, that often come up.
I have heard of a couple of successful stories though where people in essence shared land by separately buying adjoining farms or by buying one larger tract and then splitting it. (At least one previous poster in this thread indicated how they successfully did something along these lines.)
I could see that working, but I would guess that 90%+ of the time, a straight up "cobuy" would end up poorly.