I have never subsribed to UG online, however I do buy the book before each trip, and I have used TGM so I will tell you my experiences based that. When we went in June of 2004 I used the UG only, bringing the clip out plans with me. By the end of the third day, my family had hidden the book and the plans and refused to tell me where they were. It seemed like all we did was run from one end of the park to the other, and it didn't seem like we were saving that much time really and the kids were exhausted. The kids thought it wasn't a "fun way" of doing things.
In August of 2005 DH and I went alone to celebrate our 15th anniversary. I used Mike's guides to what parks to visit on what days and what attractions to see at what times. His information is updated VERY regularly, so as things change at the parks, he passes that info on to you. He or his employees are there almost daily touring with VIP guests, so he really is up on his data.
When we went on our trip I knew what park to go to, what time to be there and what attractions I could visit without a line at what times. You can follow and strict touring plan, which he offers, or you can follow his best times guide, which is helpful if you would rather have a rough outline than a set in stone plan.
By the end of the second day my husband, a die hard cynic, was convinced.
We were there in summer and we never waiting more than 10-15 minutes for anything and we had a great time!
In December of 2005 we went back again with the kids, and we had a ball. Once again we followed is guide to what parks to go to on what days, and what attractions to see at what times. Sometimes we followed his touring plans to a T, other times we didn't, that's the beauty of his plan, if you fall behind, you know right were it's best to go based on the best times to ride guide.
I hope this makes sense to you! We have been 6 times, I have spent countless hours on the Dis and have read every planing guide out there and nothing even comes close to Tour Guide Mike for us.