Old thread but since this is the first thing that Google showed me when I typed in unity vs spring.net...
Spring does do CodeConfig now if you don't like XML config
http://www.springframework.net/codeconfig/doc-latest/reference/html/
Also, Spring is much more than just an DI container, if you look at the 'Modules' section in the docs, the DI container is the foundation of the huge stack of things it does.