I think it would be an quick and easy feature to add the ability to download photo attachments from the app and save to camera roll. Yes, there is save to dropbox, but in the interest of doing a download in minimum amt of steps, save to camera roll is fastest.
Opening up the photo in safari to save to camera roll is too many steps. Also, I can’t use share to facebook because I am often commenting within a specific thread, so it’s easier for me to attach a photo from my camera roll while I’m replying to the comment.
