the only park i found it worth it was MK when i went the beginning of december. we bought them for HS as well but most things were already full by 9am though i was able to finally get on slinky but even at 7am the first time i saw available was for 7:30pm. for me epcot and AK are not worth it, but i do think the ILLs are worth the extra money, bought them for rise, 7 dwarfs, FoP, and Remy. I'm going again end of April and more than likely i will not be getting it again but we'll see.
it really depends on how you do the parks though. if you like spreading out rides throughout the day then i don't think its worth it as the later on in the day, the more likely nothing is available then. but if you like getting rides done quickly, then i think it can be worth it.