How do you define "personality"?
What I like about shrimp is that when they're thriving they are so active; constantly grazing on plant leaves, hardscape, substrate etc.
Because they're relatively small they force you to get up close to the aquarium and this gives a refreshing perspective to the aquascape. It's like a whole new world.
I'm not sure how appropriate they are in a system with minimal water changes if you're planning to keep them in an El Natural set-up.