Smooth. Like butter. My benchmark is my 2012 CAAD10, since I just don’t have enough miles with other bikes, especially other steel bikes. I'm pretty sure the tubular rims/tires on the Tommasini also really bring out its best attributes, so I’m not sure how much to attribute to the frame.
But that said, it handles beautifully, and is more responsive than the CAAD10. Probably because the wheelbase is slightly shorter, by almost 2 cm. I can dodge junk in the road so easily, and I can corner more tightly. The Tommasini also somehow feels lighter, even though it’s about 4# heavier. But
heavier is relative, it's still a very light-weight steel bike. It accelerates easily, though surprisingly it doesn’t seem to hold speed like the Cannondale.
It shifts wonderfully. I'm really not sure what index shifting adds to down tube shifters. I'll find out when I finally get my Panasonic back on the road.
The way I have it set up now, it’s almost exactly the same cockpit geometry between the two bikes, but when in the drops I’m a little more stretched out. Between that and the DT shifters, I have to be a little more alert when riding. I can’t see much speed difference based on my recent joining of Strava. Both bikes are about equally fast, at least at my current level of conditioning and ability.
Of course, this is all based on a few 10-15 mile rides. I hope to build up to some century rides over the course of the year, and I’d like to use both bikes on different long rides and see what what that experience is like.