I think you would have to be worried about him/her seeing their reflection in the glass which would stress them, as well as if any animals were in eye's view (ie cats, dogs etc), and also if they see lots of trees etc they may keep trying to get out to geth to them, but I am still a newbie here so hopefully someone with a little more experience will chime in.
I don't think reflection would be an issue as we've got double glazing which I've not seen a reflection in and we've also got a net on the window as well as the curtain. We live in a residential area so the view it would get is people's houses.