I got off an 07 Ultra onto an 09 Ultra.
Major difference to me. It is hard to describe, because I really liked the 07 ride.
I guess it's like going from a $60,000 BMW to a $100,000 Mercedes.
The ride is just more refined. Less wandering in the wind. Easier to hold a line through a corner. Brakes feel more responsive, less pressure on the lever.
The TBW is something that grows on you. At first it seems a bit twitchy, but after a few rides you never notice that, just the seemingly quicker acceleration.
I had Rinehearts, and they were loud, on this one I kept stock pipes and put in a 103 kit. 97TQ and 79HP without a dyno tune (TTS is on the way). That power and the two or three tooth larger rear sprocket make it feel much more responsive under power than my 07 with 89TQ and 74HP.
The seat is wider, due to wider frame, and the bike sits a little taller (you can tell by how far it leans over on the juffy stand). I'm 6-2, so no problem, but some report it is too tall a bike compared to pre-09's.
The exhaust is really nice, forming a neat 2-1-2. I will keep the stock exhaust as I got tired of the noise.
I got ABS, and hope to not ever need it. It does add complexity to tire changes.
The nice fat 180 rear tire now looks the right size for a full boat tourer. That old skinny MU90 or whatever just looked funny under such a big bike. But before my 07 Ultra I had a Vulcan 2000 that came with a 200 rear, and I put on a car tire because I was only getting 5000 miles out of that 135 TQ monster. Before that A Valkyrie with a 180 rear.
So far I am very happy with the 09, my second Harley, and my 15th motorcycle in about 40 years.