Hi. I joined this past month, but don't find it worth the money. I haven't even been on it since the first few days. For me, the Unofficial Guide is the indispensable book, with the Passporter coming in a close second. I bought two others this year, as well-- both a waste of time and money (Birnbaum for the color pics for the kids and a new one called Aronda Parks. . . YUCK!).
Anyways, I just don't see anything too different on TGM's than I have elsewhere. . .nothing new, nothing groundbreaking. The only benefit that I can really tell would be updated, last minute info, which would be found here and elsewhere, anyways. The kind of info that makes you groan since your itinerary and days, ADRs, etc., are already worked out!
When I compared my planned itinerary that I made with the assistance of the Unofficial Guide with his planned best days at each park, I discovered both he and the Unofficial Guide recommended parks identically save one day/one park. I am still going with UG recommendations since my itinerary is all planned and my reservations all made.
I'm thinking of getting a refund from TGM, actually, since I think it's a big waste of money for us. But, I really don't feel like even going back on his site to do it!