Few suggestions.
First, I would highly recommend trying to go the route where you're using Google sync for this instead of bluetooth. That would also allow us to text message even without the phone near us. From using MightyText, which does this through a Chrome extension and a phone app, it's quick and works very well. This would also probably be easier on battery life and wouldn't have the connections issues with bluetooth.
Second, the UI is decent, but remove the phone number input on the bottom left. Instead create a compose button. The conversation list on the left needs to be made smaller. The left side should look like the conversation list in the default Android messaging app. Mostly, the profile picture needs to be smaller.
Same thing on the top of the conversation thread on the right. There is no need for the large picture and the name, number of the person you are talking to. This takes up way too much of the conversation area when you have the keyboard open. Instead I'd like to see the list of people you have conversations with on the left. Click their name, and then their thread opens up on the right with just the text data. Change the text format to the bubbles used in the stock android messaging app. Or I would just rip off the Google Talk UI and make it dark like yours instead.
And last, the app needs a better icon. I would use something similar to the stock android messaging icon, but maybe make it blue to match honeycomb.
Those are a few suggestions, but loving the app so much right now.