How can I interpret the results of these DMVs to help me evaluate our partitioning strategy?
Rather than looking at index utilization, I'd look at the plan cache to find your queries with the highest amounts of logical reads. Usually when I'm dealing with partitioning, I find just a handful of queries that are dominating reads - like 50-80% of the servers' reads overall. Check those queries to see if they're successfully doing partition elimination.

If they aren't doing partition elimination, but you think they should (based on your partition scheme), then work with the query writers to get partition elimination.

If they aren't eliminating partitions, and they can't (because of the way the query is written or the partition is designed), then it's time to start asking tough questions.

If the biggest logical read queries don't have anything to do with your partitioned table, then move on and focus on those other queries instead.