Hi, Roxanne!
Typhoon Lagoon is a very child-friendly water park, to be sure! Be aware, though, that many of the slides will require users to carry large tubes up a number of stairs; this might be something that you'll need to help your little one negotiate.
As for being "worth it," you'll have to decide based on the likes and dislikes your travel party. Is the five-year-old into swimming, sliding, and splashing? Then a water park is likely a great fit!
What you might consider is the
Premium Annual Pass. This option includes access to: Disney's Blizzard Beach Water Park, Disney's Typhoon Lagoon Water Park, DisneyQuest Indoor Interactive Theme Park, Disney's Oak Trail Golf Course, and ESPN Wide World of Sports Complex, as well as all of the benefits of the regular Annual Pass.
Additionally, the food and merchandise discount on the Premium Annual Pass is 20%, while the regular Annual Pass offers holders 10% off. That's a substantial difference!
Currently, the differential between the Premium Annual Pass and the Annual Pass is $133.13. That difference will be quickly made up by multiple visits to the water parks and in discounted purchases. Think of it as two visits to Typhoon Lagoon, in fact, which is currently pricing at $55.38 per day for an Guest 10+.
It's a wonderful dilemma, isn't it?
See you later, celebrator,
-Deborah B.