I'm probably biased since I used to work at NI (former Michigan DSM), but I think it works great - IF you already have a requirements document.
The overhead to create/update requirements documents is what actually defers me from using it - the company I work with would rather I spend my time programming. Most of the projects I have worked on do not have a strict set of "written" requirements and things change regularly as the project progresses. My customer typically tells me what they want and then see that I met the requirements when they "test" my code. I know this is not the best way and I wish I could change it, but for now that's what I'm stuck with.
It is actually a really useful tool if the industries you work with are highly regulated. It is a quick and easy way to prove that your code has met every single requirement of a project after the intial learning curve. It also helps point out what requirements may be missing - if you have a lot of extra code that doesn't map to a requirement - was it really necessary? Or does your requirements document need updated?
One last note - make sure you are a good speller and/or double check when you type your tags. RG will pick up your tags from multiple places in LabVIEW (FP, BD, VI Prop documentation, etc), but if you mistype something - it will look like you didn't meet the requirement. On that note, if you decide to use it, do not wait until the end to run RG - run it every few days so you can find these problems early and often.
Hope that helps!
- Becky