Since I am critically minded, I will not sing the automatic praisings of Second Life. First, I will list the problems I've had installing it: well, none, really, except that it warns me that my equipment does not fit all of the requirements. These requirements are beyond the memory capacities of my computer (AMD Sempron, 3200+, 1.79 GHz, 960 MB RAM). They will probably refer to the graphical interphase, which is a matter I cannot handle. It is beyond my technical literacy.
But it works anyway. It looks like the classic video game. I have nothing against that, in fact, I agree with Game Theory philosophy: every human activity can be compared to a game with a set of rules and winning/losing criteria. The idea to use games for instructional purposes is also inobjectable. Don't traditional teachers say that kids don't study because they're playing all the time? This tool offers a way to reverse that situation.
So what's my critique? The following: At the present time, this is not for everybody. For instance, if you live in Guarenas and there is no ABA (yet, because it is a matter of time) you cannot play/teach/learn with this beautiful toy. At least not yet. But you risk flunking the course for a technical problem which is unsolvable for you.
Because the technical problems are there. Perhaps they appear bigger to you if you are not a young hacker, or at least a technologically literate contemporary adult.