In my opinion, usefulness depends on how your boat is stored.
If your boat is stored with shore power, then you can load your fridge with drinks the night before and have the fridge powered by the 30-amp shore power.
When you head out the next day, you'll turn shore power off and switch the fridge over to your 12v batteries to keep your drinks cold throughout the day.
My boat is rack stored. No 30-amp power. So the fridge was less useful to me. If I loaded it with drinks at the start of the day, they might be cold by the end of the day! The ice box did a much better job of cooling things.
What I needed was storage space. So I removed the fridge and a company in Tampa shipped to me a nice, deep, custom storage compartment. All of our microwaveable, but non-perishable, food goes in that compartment during our boat trips.
We'll bring a cooler on our boat trips and just add a bag of ice every day or two for cold drinks.