How to do evaluation when the methodology is unique?

When it comes to the evaluation of a methodology (or an algorithm (CS)) we usually see how well the methodology actually is by comparing it with other similar methods that achieve the same thing.

However, in my case, the method we are proposing is unique and novel and, to best of my knowledge, isn't used anywhere else. Is it valid to evaluate it on its own, for example by simply measuring its time/complexity against n datasets? How would we perform evaluation for methods that can't be compared against others?