I have the desire, my friend has the galaxy. The ONLY advantage over the desire is that it has a better screen, but that's not to say the desire has a bad screen because it's brilliant, but the galaxy's screen is better. I don't like the feel or the build of the galaxy either, it's very cheap feeling. Also it doesn't look very nice being an iphone rip-off. I do like the swype feature, and that is the only thing that I would want the phone for. However swype is working on a release for android phones, and often opens a beta download.
The desire is MUCH smoother also when moving between screens. The galaxy looks choppy compared to the desire, which is as smooth as the iphone.
Overall I'd say the desire is a lot more perfected. On paper the galaxy should have the edge, but having tested both, the desire is much more enjoyable to use and also easier. Also it has better home widgets.