Dan's design was definitely superior, and he had come up with so many creative and beautiful solutions that met the clients' needs. But I was pretty sure that, short of really screwing it up, Antonio had it in the bag. The judges seemed to really like his "in your face" hosting style. Dan was still finding his way as a host, and even when he got there, he was going to be pretty much like every other host. I think the judges really wanted Antonio with his unconventional style (although there is a landscaper guy on DIY network--his show has the word Dirt in the title--who is very similar to Antonio in his style, so his approach isn't totally unique).
I wasn't surprised by the decision, but I did feel bad for Dan, because he mostly knocked it out of the park with his designs (although I didn't get the "Spring" theme, since he didn't use many colors that I would think of as spring colors).