I think it's a great name that works both ways. I went to school with a boy Kelly who'd proudly say "Kelly was a BOYS name first" and a pair of Robins, one boy, one girl. Maybe my elementary school was a little liberal on names but Kelly and Robin were never teased.
Having said that I do find it a little trendy but all the Averys I have met (both boys and girls) have suited their name so well.
I know that it is a masculine name, but I know tons of Avery's and they are all girls. The only boy I have met with the name, was a little boy at the daycare where I use to work at, ten years ago. I would never name a boy Avery just because of that. But it could be different in your area, in my area, it is #14 for females and not even in the top 100 for males.
I wouldn't use it for a boy. Once a name has become predominately used by girls, I wouldn't use it on a boy. My husband is a Robin and is a little insecure about his name. He especially hates getting emails/calls addressed to Ms. If Avery weren't SO popular with girls, I think it would be different.
I like the name, but I personally wouldn't give a boy a name that girls are predominantly using right now (I also won't give me girl a boy name even though that is 'trendy' right now). There are lots of good names left out there that clearly masculine/feminine.
Re: Avery
Maybe my elementary school was a little liberal on names but Kelly and Robin were never teased.
Having said that I do find it a little trendy but all the Averys I have met (both boys and girls) have suited their name so well.