There are some big problems with iMessage service, If we do group chat or messages, the group will be fixed and not editable, we can't add new members, or delete existing ones. Some people will not be convenient with some groups that other people add them to. Some users will keep chatting all day, and notifications will keep coming. and this is really annoying. We can't leave the groups, and we can't at least stop the iMessage groups notifications. we have either to stop the whole Messages notifications including the SMS, or accept the fact of the Inconvenience. I have already sent a complain to apple regarding this, and i hope you do the same to push apple to consider this issue.