If you can go, there's no reason why you shouldn't.
The view is spectacular, the food is excellent, everything is well designed for you to have a lovely dinner.
We made a reservation 2 days in advance and we got a nice table with the view that you're looking for. The place is really crowded at sunset and the good view is limited to a few tables.
At sunset, the tables with the view are separated with a rope, so the people are not barging in your romantic dinner, a very nice idea.
We went by foot from Sidari, it was a lovely walk, but when you return it can get a little too dark, the roads are deserted, the only thing that you hear are the dogs from far away.
As a suggestion you can walk to the restaurant and come back with a Cab/taxi, or take the cab to the main road in Sidari to avoid the deserted surroundings.