I had lunch at Infante 51 with some work colleagues earlier this week, I found the overall experience to be a very positive and enjoyable one. Infante 51 specializes in seafood, but they also have other options that should appeal to those not inclined to seafood.
The layout and design of the restaurant is very nice, and the service was very friendly and attentive. Two of my colleagues ordered unique Chilean fish dishes and were very pleased with the preparation and taste, I ordered crab ravioli and was also very happy with my dish. The appetizers were also quite tasty.
If you are staying in the Providencia area and are looking for a nice lunch/dinner option, I think Infante 51 would be a very good choice for a meal.