We did this a couple of years ago. The ship is small, but built for the number of people it hold so you don't feel crowded. Cabins are MUCH smaller than Regent, but you really don't spend much time in there. Food is just ok. They have to use only local produce and meat. THerefore, stay away from the beef (when you see the cows, you will understand what I mean). The fish is good, and the ceviche is great.
They have a nice salad bar at lunch which is pretty much what I ate every day. Also a buffet for breakfast which was adequate with omelets made to order. Dinner is off a menu, usually with 3 main course offerings. I thought the salads were pretty good. Desserts--I can't say as I don't eat them.
Drinks are included. The bartenders make a great margarita. Beer and wine are free-flowing. The wines were Chilean and ok--nothing expensive though.
Take lots of sunscreen, shorts, hiking shoes. Some of the areas are really rough as they are volcanic. I took my walking stick and used it. One lady fell on an excursion and got a really deep nasty cut on her forehead that required several stitches, so be cautious. It is easy to get looking at the wildlife and surroundings and take a mis-step.
You will sweat a lot. I had laundry done a couple of times, and it was quite reasonable. There is no self-laundry.
My favorite spot to relax and read was up on the top deck. There are some nice loungers there.
Any other questions--just ask!