My wife's phone has been having a lot of trouble with texts as described in this thread. She uses Handcent. She does not use Google Voice, so her texts are going through Sprint only.
I don't have as many troubles as she does. (Although I don't send nearly as many texts as she does.) I have been using the stock app. The only time I was really noticing having trouble was when I was futzing with Google Voice setup a few days ago, after updating to ICS. I attributed those problems to me getting GV balled up.
My wife claims her reception is not nearly as good as it used to be either, with lots of dropped calls.