This was the first spelling of the name that I learned, since a girl in Kindergarten was named Hailee. To be honest, I think that it’s a very cute spelling, even if I do prefer Hailey, Haley, and Haleigh. If you like this cute and different spelling, I say go for it!
I'm a little inclined to pronounce it "Hi-lee" or like the word "highly". It's not the worst variant of Haley (which I'm not the biggest fan of anyways) but I don't really care for it.
Hailee is a beautiful name. I named my daughter Hailee in 04. I know of no other person with this spelling. I wanted her name to be a little different. Her nickname has become "hailcat" which really fits her personality.