I just have a couple of comments:
1) The people who don't like it and say their BA/SM has plenty of power, why would you change?
2) The people who don't like it, like their bike, but want more power, you really should consider adding the BigBore kit to your bike. For only $1200. I had mine done including labor I gained almost 50% more torque and power. I couldn't be happier with what I have and I was considering a bigger cruiser.
As far as my opinion, I'd have to see it in person and hope they do make some cosmetic design changes. I think straight pipes would look better and would like them to figure out how to have a more Triumph looking tank. Right now I still think the engine looks like a french robot wearing a blue beret.
If my bike got totaled and it was between my 904 05 America all tricked out and a new BA/SM, I'd definitely consider the Thunderbird - for now, no.