Re: They should have bought Prezi.com
The bloom is already off that rose. For the past couple of years I've heard frequent complaints about Prezi at conferences - people complaining that it adds too much noise (in the form of pan/zoom/rotate visual effects) to presentations, that it's too much trouble coaxing it to work in the often rather hostile IT environments of conference hotels and the like, that its main purpose is to put lipstick on the pigs of poorly-written and -designed presentations. I've even seen a number of people complain in print that Prezi presentations make them dizzy or nauseated.
On the other hand, I don't know what, if anything, makes Slide Share any more valuable than any other site where you can store presentations, aside from its (claimed) relatively large user base. It always struck me as pretty boring.