Great library for Test Driven Development. One day all programmers will work this way!
Easy management of test suites, in-depth automation via ruby scripts, specialized assertions, specialized for portability, extensible, friendly support - thats how I got to know Unity (v1.2.1 in conjunction with CMock). It really is especially useful for testing embedded systems be it system tests on the target hardware or mere functional tests on the development environment. But in all honesty the automation of the framework is especially stunning and it is what makes this so much more efficient to use than other testing tools.
I'd love Tests, and Unity is a fairly easy and small unit test framework!
OK, yes I am one of the main authors of this package... but I use it every day and can't imagine writing C without it.