Overall, this is a decent chatting app with some nice features. But it is highly susceptible to spam.
There is the ability to just talk to "nearby" this app users, even those you don't know. So I've received some inappropriate spam messages that way. If there was an invite feature, where instead of seeing their message and profile pic, it just had the message "X would like to chat with you" and you could accept or decline, that would make GroupMe 10 times better. Of course, for those who want the ability to get messages from anyone, they could turn invites off.
The other thing GroupMe needs is a way to actually delete chats. Yeah, I see the pros of always having the chats and groups if you need them again, but as I said earlier; there is some spam that I would like to delete, not just hide. Because once its hidden, every time GroupMe updates, all those spam chats come right back to the home screen, and I need to spend time dropping them into hiding again.
If these features are added, the current abilites to send messages to people with just text or email make this a fantastic app.