I've cruised on the Sun twice, once when it was a Cunarder and after it became Seabourn.
Personally, I thought the food was outstanding, especially in the casual lido restaurant. I'm not a fan of assigned seating, but I understand the reason (size of ship, number of passengers). I had a snooty waiter the second cruise, asked to be moved and was thrilled with my new waiter. He did get me some lighter cuisine.
Like all small ships, the entertainment is lousy, unless you're in your 80's. And this isn't because all the passengers are elderly. On these size ship there are very limited facilities for much entertainment. A floor show (ouch!) and piano bar, etc.
But itneraries are outstanding and the ship has a very homey feel. It's the perfect size for me. Please come back and give us your report. On both my cruises, I had a wonderful time.