My husband and I booked our tour with Victor via email about two months prior to the trip.  He was very communicative and accommodating so it was easy to get the logistics down.  The hotel room that we got as part of the tour package was also very nice.  It's called the Daekuk Isle Inn Hotel and it is located very close to the limousine bus stop (walkable but more easily accessed via taxi when you first arrive).  It was clean, comfortable, and had an excellent included breakfast (you can get both Korean and Western-style foods).  The staff was friendly and there are computers you can use with internet access. 

The tour itself was fun--be prepared to wear appropriate footwear because you will be doing a lot of walking and some of the surfaces will not be very easily-managed if your shoes are not secure.  We were able to see a lot of beautiful sights and our guide was very knowledgeable about the ecosystem, the culture, and really anything we asked him.  The group we were with was also smaller than I expected--the first day there was six of us and the second day there was eight.  We were from all over the world which was also fun.  As a person of Korean heritage, i have to say I enjoyed the traditional Korean restaurants we went to for lunch.  My very American husband also enjoyed the food once he gathered the courage to try some of it :) 

Throughout the tour, I did not have any worries because everything is clearly taken care of before and during.  I highly recommend Jeju Eco.