The number is real, but seasonal. The valley's 72 waterfalls are fed largely by snowmelt, so the count you'll actually see depends on when you come: May to early July is maximum flow, when the cliff walls genuinely stream on both sides; by late September many of the smaller falls reduce to threads. Two are worth planning around specifically. Staubbach Falls — the one behind the village church in every photo — drops nearly 300 metres in a single free fall, one of the highest of its kind in Europe, and it's free to walk to (there's a path behind the spray in summer). Trümmelbach Falls is the oddball: ten glacier-fed falls inside the mountain, carrying the meltwater of the Eiger, Mönch and Jungfrau — up to 20,000 litres per second — reached by tunnel lift and galleries. It's the only one with an entry fee (about CHF 14) and the only one worth it in any weather, since you're underground anyway.
Do you need a tour for the waterfalls? Honestly — no, not for the famous two: both are reachable by valley bus or a flat walk from the station. The 72 Waterfalls e-bike tour earns its price by covering the full valley to Stechelberg — the stretch most walkers never reach — with a guide who knows which falls are running that week. If you only have two hours, walk to Staubbach and take the bus to Trümmelbach. If you have half a day, the e-bike shows you the whole amphitheatre.