We too disembarked Navigator December 1st.
We also sailed on Explorer in April.
Our experience on Navigator was completely colored by the horrible way corporate (read ADM) responded (or not) to the wholesale port cancellations and itinerary revisions we were forced to endure. I agree with the many guests that believe Regent has lost their customer focus and perhaps many previously loyal customers.
For us the service onboard was outstanding, with few, if any, misses. The staff bent over backwards to serve our every desire. As good as any we have experienced on eleven Regent cruises.
The food had some serious misses, especially with inedible beef on multiple occasions (could not be cut with a steak knife) and a similarly tough duck magret. These issues were addressed with the GM, head of restaurants and the head chef.
Otherwise, we enjoyed our food and twice did special order dinners (dishes we love from Pacific Rim and Chartreuse on the Explorer) that were fabulous.
So, a mixed bag.
We did not book a future cruise with our fcc yet, not sure if we will.