Formal methods are not easy without strong discrete mathematical skills. On the other hand, their use (even on the back of an envelope) can aid significantly in uncovering problems in many aspects of software development. At least one person on every project should be comfortable with formal methods to ensure that opportunities to building quality into the product are not lost. And that requirements are properly understood.
Many people think that the only way to use formal methods is to specify a system completely using them. This is not true. In fact, one of the most effective methods is to write a natural language specification first. Then attempt to write parts using formal methods. Just trying to write things more formally will help you find problems in the natural language. Fix the natural language and you now have a better document. Discard the formalism if desired after it has helped you.
Reference:
Hall, A., "Seven Myths of Formal Methods," IEEE Software, September 1990.
