I've been to many resorts around the world and this one tops it!
First, the location. The hotel is accessible by airport limousine bus, Seoul metro subway, taxi, etc. We took the limousine bus since we had lots of bags and children to bring along. It was super easy to find the bus right outside the arrival gates at ICN and we were dropped off a few steps away from the hotel lobby. Took about two hours.
The food. I loved the breakfast buffet at La Seine. It had options for everyone, including my French Canadian wife and kids. Loved the high quality protein, salad and fruit options. The hotel is also connected to the Lotte department store, at which the B1 underground food market has really cheap, but great food options as well. We had dinner there a few times.
The amenities. The gym and the swimming pool were great! Gym is well equipped, I used the full set of dumbbells, incline step machine to get my daily workout in. The kids play lounge was also great for our 4 year old and our 7 month old. It was full of toys, virtual activity screens, etc. We also loved the fact that the hotel had a dedicated entrance to the Lotte World, so we could skip the lines and go in and out with our day pass.
And lastly, the staff. I must say this is the friendliest, warmest, and the most professional hotel I've ever encountered in my life. Huge kudos to the management team and staff for maintaining such high quality guest experience. All in all, it was a perfect 5 night getaway for us!