I have tried all of the above and nothing works. This is incredibly frustrating. They should be able to put the original version of the messaging app back in an emergency release, then figure out what went wrong before they re-release a new update.
I tried DJ_Damjano's suggestion too. After waiting overnight I was able to see the message thread. As soon as I answered a new text in that thread, it went back to its old behavior.
I'm so sorry to hear that you're still experiencing your issue. You said you've tried all of the above. Is this including a factory reset?
I fixed mine awhile ago. Sorry I have been MIA from the forum lately. Here is what I did.
1. go to the play store. download sms backup and restore. (This is just the one I found worked best after trying 2).
2. Install and open app. Run complete backup of messaging. I have an SD card I believe I had it save to that location.
3. Wait. this took awhile to backup. I can't remember for sure but I'd say at least a half hour. (turned out I had 35,000 text messages on my phone)
4. Then from this same app you have the option to delete all messages. don't select the "delete backups" option as this will undo what you just did. Selecting the "delete messages" button will then delete all messages on your phone in the native messaging app. I believe it only deletes the actual text messages and not picture messages. the picture messages will remain in the native app for messaging.
5. Open ur native messaging app. Should work now and not give you the "please wait" for more than a minute or two.
6. (optional) I chose not to restore my messages from the sms backup. going into sms backup I am still able to access all of my texts by conversation so I opted to not restore them; figured this would only bog down the app again.
Since doing this I havent had anymore texting issues. I now use google voice messaging widget as it is convenient and the widget is kind of nice too. This seems to be slightly faster as well. although it doesnt save every message from what I can tell.
Hope this helped. Now that I got this problem fixed I am really enjoying ICS. Has some nice features and using google chrome as a browser is really nice.