Once you have made changes to your assessment and feedback strategy and practice, you will want to know what the impact of those changes has been for your students' learning. There are many ways you can consider this. Changes in course satisfaction ratings in end-of-course surveys or changes in NSS or PTES scores may well give you some ideas about how your students are responding to the changes. Improvements in grade across a cohort will also give you valuable information.
However, you might also want to consider evaluation by asking your students for their thoughts. If you decide to do this there are a number of ways to collect the data, but before you begin, be really clear about what you want to know. For example, do you want to find out if your students felt that the assessment really did test their knowledge and skills, or if they felt supported throughout the course with the feedback that was provided, or even if they felt that the course supported them in learning for their while programme (was it an integral part). You might also want to consider asking them how to improve the assessment and feedback for your course and perhaps even getting them involved in the redesign.
Note: If you decide to evaluate your changes, you might also consider getting ethical approval so that you can publish your results, but publication is not essential.