We used G+ and ILL when we were in DL in March so I knew the system. I really feel as though we got more out of it at DL as compared with WDW. I suspect that this is a combination of a few things that are all tied together.
1. Area of each park. When you compare the parks and their acreage WDW parks are all larger than DLR ones. Going from largest to smallest on each coast: DL 98 acres, DCA 72 acres. MK 106 acres, HS 136, Epcot 299, AK 580. The larger size means a lot more walking back and forth to get to the LL rides we were able to book.
2. Number of LL rides in each park. This goes hand in hand with point #1, When you remove entertainment and character meets from the available LL attractions and only look at rides, there are as many or more LL rides at DLR when compared to WDW, with the exception of MK. (We only did MK for the Christmas party so LLs were not really a factor at all) DL 12, DCA 8, MK 16, HS 8, AK 5, Epcot 9.
3. Capacity. Given the larger area of WDW parks, although the exact number is not know, it is safe to assume that the capacity of the East coast parks is higher than those on the West coast.
So, when you add all three of those things together, you get more people battling for fewer LLs, and more area to walk between rides. All of the "top tier" rides sold out of LLs pretty early in the day and when you factor in the 2 hr wait this meant that there were LLs we were just not able to get.
Oh, and HS...wow was that a mess on the 18th! For quite a bit of the morning there were 4 attractions down at the same time! ToT, RnR, SDD, and M&MRR were all down for a significant portion of the day. This put a TON of pressure on the other attractions and made for some insane posted wait times! We ended up getting a LL for AlienSS, M&M, and paid for RotR. Definitely not worth the $ we spent on G+ that day.