I'm really glad to see you all talking about this.
Becky, I had a similar experience. I had seen people playing with the app and laughing at it, so then I tried it out and it took my breath away. I was just utterly blown away by what I saw. I then became obsessed with the app, taking 20-30 selfies a day. This is something I never do, I rarely take pictures of myself, and I don't look in the mirror much, but I just had to keep trying to see these pictures of me as a woman. Something I had written off as impossible and suppressed.
I've only recently started to cool down on this app, because it is full of problems. It always wants to lighten my hair, make my eyes bigger, and shrink my chin and neck. After looking at some of my favorite pictures for a while, I've ended up deleting them because they are just too distorted. I try sometimes to break the system and make sure it acknowledges my chin as it is, eyes as they are, but I can only do so much. It seems to me that it's time to just stop using this thing, because it hurts when I see an image and then believe it to be impossible. The opposite effect of why I started using this app in the first place.
That all being said, I am thankful for the good moments it brought. I am thankful that it made me actually want to take pictures of myself, and to smile and be expressive. I'm thankful for some of the Female-Face images it gave me, the ones that really resonated, that made me say "That's me!" I keep some of them in my heart, and I have at times been able to carry them with me in my day to day. To allow 'her' to be the one who is talking, walking and being 'me,' even if I am full-time cis presenting.
I have a long road ahead of me. I am thankful for this face app, but i am also very wary. It can be addicting and ultimately deliver empty promises.