It's very very popular (1-2 in most yrs at our school, and muddled in my head with Ella, Ellie and Amelia) but, well, for a reason - it's a nice name (they all are).
Everyone can say it and spell it. It's fine.
I wouldn't pick it as the one thing I like about my own name is that it's unusual (so when I call people I am the only Clary they know).