Should I play Cave Story+?

Never played Cave Story, but I have Cave Story+ from one of the humble bundles a while back. Is it worth installing? Or too dated/old news to bother?

Play it. It's not too long and pretty fun

It has an end? I somehow always pictured it like Runescape, where you just leveled up forever and multiplayed in random things.

Does it actually have a story or something?

It's a sidescroller, I don't even think it has multiplayer.