More than anything else on a phone, the messaging service is what I make the most use of, at least up to this point though the Pre's excellent web functionality has it gaining in market share of my mobile time use. For the most part, messaging works unobtrusively on the Pre, but as always, I am here to offer a few suggestions on how it could be better in my opinion.
Along with text messaging there is built in support for instant messaging platforms as well, but only AIM and GChat. My first suggestion is obvious, add more platforms. Yahoo, MSN, Facebook et cetera. Another minor issue is the integration of text and instant messaging does not always work smoothly and I would prefer to leave the default application to text messaging only.
Perhaps a third party application like Digsby could come in and really provide a killer solution because having a third party application to let me handle chat accounts would be ideal. Hopefully, much like desktop applications, it would also be able to deal with the various platforms independently so that you could, for example, mark yourself as away on GChat but available on AIM.
My last suggestion is probably a bit more difficult to achieve but is something I would really enjoy seeing and that is to really embrace the card nature of the webOS and take a lesson from Firefox 3.5 and implement a detachable card for text messaging conversations. I feel it would lend a more efficient system for those who deal with a lot of texts from a lot of different people simultaneously. I find it easier to switch between cards than to back swipe to the home screen in the messaging client and then tap on the next conversation to comment in.