What I've noticed is that:
Messages don't seem to work right with standard email programs like Outlook or Outlook Express. If anything in the thread was posted from a smartphone, the thread is "poisoned", and the only way for your reply to show up is to copy the earlier stuff into a new message.
If you just reply, everything you add is stripped off.
Messages are unsearchable, many photos are messed up, multi-sized options don't work, you just get the thumbnail.
It seems to be a mess.