Very interesting, i wonder how Epic will deal with the actual deployment of an .app. At the moment its OSX only, as any .app developed, needs the provisioning files, certificates and the .app uploader all on a Mac.
Silo is a great app if you're just starting out, it doesnt have the advanced features of the bigger apps(rendering, animation, etc) But it is a nice streamlined and focused modeling app, perfect for begginers i'de say.