Whenever I post to a TGM thread it invariably, albeit quite unintentionally, turns into a eulogy so I don't imagine this response will be any different. I'd like to preface my answer this time by saying that TGM isn't some kind of holy grail, but neither does it claim to be. For some reason, there's this myth that you'll discover all kinds of insider information not available elsewhere and I think that's what can often lead to disappointment. If the subscription cost was $50 a year, then one could be justified in expecting something more, but the value needs to be judged in light of the cost - most of us wouldn't think twice about paying £10 for a guidebook. (Actually, when I first subscribed many years ago, there were, without question, a fair few secrets to be gained from membership, but over the years that's become diluted through inevitable leaks. Whilst most TGM subscribers are undoubtedly people of integrity and wouldn't dream of blatantly passing on proprietary information, once they've taken advantage of a particular tip themselves, it's no longer an abstract concept: it becomes their own experience and there's no way of preventing people sharing that with others. So, whilst I can go along with the argument that most of the information is available elsewhere, it's also fair to say that he was the original source of some of it and, in his position, I'd be pretty miffed!)
Having "masses of information" wouldn't be a criticism levelled against a guidebook - it would be considered a bonus. We don't find guidebooks confusing because we know how to use them. Even the simplest of websites can be difficult to negotiate until we establish a "mind map". TGM's offering can be bewildering, but understanding its separate components can help in getting your head around it.
Firstly, you have what boils down to an online guidebook. It contains all the information you'd expect to find in a fairly familiar format: the parks and their attractions together with ratings; hotels; dining; tickets; special events and so on.
Next up, you have TGM's "Vacation Articles" which are effectively his tips for getting the best out of your visit. This covers a huge array of topics including (to name just a few) the best places from which to watch the fireworks and parades, how to make the most of the transportation system, securing your choice of hotel room, what you can expect in terms of crowds and weather during each month, strategies for special events, and sample touring plans based on your party make-up. Also part of this category, but worth a separate mention, are his "Least Crowded Parks" charts. For each and every day of the year, he shares his thoughts on how busy each park will be and why. Once you've been a subscriber for a while, you start to get behind his thinking and it's perfectly possible to work it out for yourself, but I do like to read what he has to say and I still think it's worth the ongoing subscription cost (less than £5 a year) for this information alone.
Where all this differs from regular guidebooks is that he is in the parks every day and has studied crowd patterns and behaviours to the nth degree, turning into something not much short of a science.
Then there is the real-time content. When I first became a subscriber, this was TGM's USP. I could log on each day and be the first to know about
anything affecting WDW. The information was bang up to the minute and
always accurate. Park Hours were available there ahead of anywhere else on the internet (often days before Disney published them), hotel discounts, dates for special events - you name it, TGM had it first. Sadly, this is no longer the case. I've no idea why. Maybe TGM doesn't have the insider contacts he once did; maybe he's lost interest (this is just a sideline for him, after all).

As others have said, he no longer publishes his Least Crowded Parks charts in a timely manner and, if you're relying on this information to finalise your itinerary, you'll be behind the game in making ADRs and the like if you wait until he's published it). I do admit to being disappointed with this turn of events - his service is nowhere near the exceptional one it once was.
The whole thing comes together as an interactive planning tool. When you subscribe, you input your dates, details about your party, preferences, where you'll be staying and so on. The software then pulls together those articles which best suit your circumstances to form your own "Automated Vacation Planner" (AVP). It isn't personalised, as such, but neither are you restricted to just those articles. You have access to everything on the site and can add or delete articles within your AVP. Each restaurant or activity you add to your planner, is included in a list detailing when your reservation window opens up and you'll also receive email reminders. Other tools include "Calendar Clipboards" and "Express Planners" for each month of the year. These are round-ups of all information specific to your date of travel.
So, in summary, it isn't as good as it once was, but it's useful to have as part of your overall planning toolkit.
