We just returned from WDW and didn't do the Frozen package, but we did watch the welcome parade and attended the sing along. The group we were with didn't want to stay for the evening fireworks, including my DH, so I missed those.
If you decide to do the sing along and not the whole package than make sure you pick up your free tickets as soon as possible upon entering the park in the morning. They only give out 1000 tickets per show and they go fast. My group thought the sing along was great.