I just tried uploading some of my files to compare this service with the other prototypers that I currently use. Overall it has been pretty painless and I'm really excited about it. My one complaint at this point would be the need to upload every part of an assembly seperately. It would be much more convenient to combine all of the *.stl files into one *.zip, and then add descriptive text for each of the files after uploading. This is how files are uploaded to other prototyping houses and it saves a lot of time.