In summary- waterfall/atrium is impressive and a must see. Rest of Jewel is an expensive mall that can be skipped. Plan your visit strategically if an airport passenger or you can get stuck on the wrong side of the glass or dealing with luggage hassle.
The waterfall atrium is impressive, no question that you need to see it if you are in Singapore or passing through Changi Airport. HOW you visit it is the difference in experience. The Jewel is really the waterfall/atrium surrounded by a giant mall that attracts what feels like half of Singapore. So the bulk of the people there will be locals slowly wandering around a mall, not travelers lugging their suitcases.
The suspended walkway, hedge maze, canopy climb and anything else they can think of is now a ticketed experience (quite expensive for the relative product). All the stores in the mall are high-end, not sure why any traveler would want to actually shop there, but the locals do.
The Jewel is outside immigration, so A) if you are transiting Changi Airport, you actually have to leave to visit the atrium, otherwise the best you can do is the SkyTrain which passes through the atrium (T1-T2 or T1-T3). Make sure you have the necessary time and paperwork to do so. B) if you are staying in Singapore, visit the Jewel before you head into the Terminal and pass through immigration. This can be done by early bag drop at Changi L1 (only if traveling to an approved country, and USA isn't one of them) or by visiting the Jewel without dragging your luggage along (think of it as a tourist attraction and go hands free) or be prepared for a TON of hassle dragging your luggage around.
We made the mistake of going hours before our flight, only to find we couldn't drop our luggage at the Jewel Early Check-in because USA isn't approved by Singapore Airlines for it. So luggage storage cost us S$40 for 3 pieces. The bridge from Jewel to T3 for example is VERY VERY long and crowded with locals connecting from the MRT. It was a huge pain and Changi signage actually was surprisingly lacking.
Light show was nothing special. Go see Spectra at the Marina instead.