As someone else has pointed out, it's an irrelevant protocol until it's made an open protocol. This will join the pile with FaceTime, iBooks, etc, that exist merely to lock people into Apples 'garden'. People should want to use your platform, not be forced to remain there cause they have to. Provide an open protocol, and make people want to use your products because you have the best implementation of it.
I understand the technical issues at hand, and I don't want to dismiss them as being unimportant--because they are important. However, the majority (who are non-technical end users) simply don't care.
Security is great, and everyone wants to know that their text messages are as secure as possible. When it comes to iMessage, however, I've yet to meet a single regular user who counts improved security as a reason to use iMessage. Heck, none of them even think iMessage is more secure than a regular text message.
What do they use iMessage for? It tells you when someone read your text. It tells you when someone is responding. It sends faster than regular text messages and confirms that it's actually been sent. Even more importantly, it allows us to send international text messages for free. As a Canadian being charged $.35 per text to the US (even though US and Canadian numbers formats are identical), this means I don't need to reroute a Google Voice number through 3 numbers just to keep in touch with my US friends.
The selling point of iMessage has never been technical; it's been functional.
A lot of the people out there using iMessage don't even know it. Because it hooks in so transparently with text messaging, people who used to SMS between iPhones now iMessage between them and many don't even realize that anything has changed.
Among those who do know the difference, my experience is that by far the most common reason to use it is to avoid paying for text messages. (I'm in the US here, so it's common.) A secondary reason, but really secondary compared to that, is the fact that it works on other iDevices, not just iPhones.
Until I read these comments, it didn't even occur to me that security might be an advantage of iMessage. I think the number of people who use iMessage because of that is roughly zero.
Not really. iMessage can be used in a transparent way with non-compatible devices (it can just fallback to sms), and it merely loses its advantages. People won't care too much that it's closed, and will still use it. And it won't lock them. If their next phone isn't an iDevice, they will just go back to sms.
FaceTime doesn't fail merely because it's a closed protocol. It fails because it's a closed protocol and the application has no way to fallback to other networks in order to communicate with non-Apple people.
that exist merely to lock people into Apples 'garden'
You don't think providing good features to users or creating a competitive advantage has anything to do with it at all? I agree lock-in is part of the equation in large part because Apple doesn't care about other platforms but there are definitely many other reasons these things exist. When/If it's in their best interest to support other platforms they will. (iTunes for Windows, for example)