That's a broad statement. It's not good if you don't want the phone company (and anyone else who can have access as a result) having a complete record of every conversation you have through messaging.

It's not good if you want some features offered by modern messaging clients.

It is good that it has been adopted as a standard.

If you just want to tell someone hey in a standard way and don't give a damn who sees it then sure, it's good.