My dad flew in from KL over the weekend just to visit Jewel and was somewhat disappointed (given the huge amount of hype).
✓ Yes the architecture is amazing, and yes the waterfall and forest / garden is nice.
✕ But aside from that, Jewel is just another mall with 90% the same restaurants and shops that you can find in any other large mall on the island.
btw I had a group of friends who queue'd for Shake Shack, and ended up with an almost 4 hour total wait from queue to food ...