The only version of Cave Story + on the switch that is worth money is the launch version with all of the physical goodies, namely the key chain that I sent to tpcool and then he sent his to the wrong address and so instead I get like $20 and never got the curly.
The instruction booklet is pretty rad, the hint for the hidden ending was actually really clever, and I applaud NICALiS for that.
In terms of the game itself, the new lighting, water physics, and other awesome visual changes are already enough to sell me, but the multiplayer feature was something that sold me, but sadly, when NICALiS makes a game, they never update it in any meaningful way, and that includes a lack of online multiplayer.
Also one of my favorate features that they didn't advertise was the new Ridiculon soundtrack, alot of people say it sounds like shit but I disagree, it's a polar oposite of the wiiware soundtrack in that it doesn't change the melodies at all, but has orgasmic instrumentation. It gives the game a new feel, one that with all the new upgrades they had made, doesn't feel out of place.
If you stop being stingy ignore the price point, it is the definitive version of Cave Story thus far, until a new system comes out that warrants another release.
If you want NICALiS to keep making things related to Cave Story, then buy the Switch version, and maybe there will be an off chance that they actually do something really great with it.