The only problem I had with the stock app was the group messaging.... Sending to multiple people was never an issue, the issue was when anybody replied back it showed up as a new text and lost the group thread. Happened every single time but never happens with GO SMS. I was a bit surprised since the Rezound I came from treated group texts just like the iPhone does (must be the way HTC made the app in sense).
But, like others have said 3rd party apps work perfectly. I prefer GO SMS because it works perfectly and looks very nice too