I got some frosted ultra detail ships from shapeways and I wasn't really happy with them. The designs are excellent but the printing lines were pretty clear when painted, and in the end I decided I couldn't use them. Others may disagree, but my opinion is that the frosted ultra detail isn't really up standard yet. haven't tried the frosted extreme detail though, it might be acceptable.

I hope they do get it to work, I think shapeways is a fantastic idea and there is some really excellent design work there, but for me at least I couldn't recommend it just yet.