It really is amazing! Like being in a wind tunnel almost. Got to go on the Shinkansen from Kyoto to Tokyo and back. Expensive but wouldn't have been a visit to Japan without it as a train fan.
It’s expensive if you reside in Japan. If you’re visiting you can get all-you-can eat rail travel (including Shinkansen, though only a limited choice) for relatively little money, e.g. one week for less than $300 and two weeks for less than $450), see https://en.wikipedia.org/wiki/Japan_Rail_Pass.
It’s great, but make sure to order it before you get there.
And there are calculators online to tell you if it is worth it for your itinerary.
The Japan Rail Pass doesn't let you ride the fastest Shikansen variants (namely the ones that stop at the fewest stations), FYI.
Unfortunately it wasn’t planned so I bought it on the spot. Cost £200 or around 28k yen.
Same for me, going from Tokyo to Osaka was an amazing experience. It only saddened me when I returned (New Zealand) and realized how much better tourism would be here if we had a similar way to travel from Auckland to Wellington/ChCh/Matamata/Rotorua. I would definitely save just to travel within New Zealand (roads are narrow/hilly/curvy, buses take a long time, ferry not available everywhere, air travel expensive and limited too).
Japan has initiatives like these because there's cross party consensus that they're a public good. I can't see it happening in NZ with three year election terms and the policies of the National Party (et el) heavily favouring road over rail.
Not to mention, you know, the cost of high speed rail in a country of 5 million.