It's more of a game changer than any other advancement in electronics within the last couple decades.
You will catch more fish with it, but you can (and probably already do) catch them without it. It's really more of a question if you are willing to spend the money on a toy that will never pay for itself.
And yes, you really can't compete with someone that has it. Especially for crappie.
What I liked about it more than anything, was being able to get a perspective of the bottom by looking 50+ feet in any direction while sitting still. Really helps you zero in on a brushpile, plus you can easily see if anyone's home. With 2D you are limited to what you can see in the cone, and you have no perspective when the boat is not moving.