I considered EGS as well as a sort of back-up option had I not gotten in anywhere else - the faculty is outstanding indeed. It does seem almost a little too good to be true, so I spent awhile researching it and found out that it isn't really accredited by any typical standard, and that the program is pretty much entirely run by one man. Eventually I actually met someone who had attended EGS, and he described it in positive terms to me as a kind of philosophical summer camp. The students are very international and of a good quality, although he surmised that it is probably true that they accept anyone who applies and is willing to pay the tuition. He did say that the most active and ambitious students did get to be advised by Agamben and the like, so I think it's no joke if one puts in enough effort.
It would probably be unwise to turn down any real, accredited institution in favor of EGS, but in addition to actual grad school it could be worth it. I actually first heard about the program when I was interning at an academic-type publishing house and I read over a manuscript proposal by someone who was getting his doctorate somewhere in the States at the same time as attending EGS during the summer (he bragged of studying under Zizek). So if you've got the extra cash, I'd say go for it if you're really interested.