I cruise with many cruise lines, so I am no super expert in Seabourn. And due to years of Covid interruption, my information on Seabourn might likely be outdated. But I'll tell you as much as I remember.
I think Seabourn has very good service in general. Some staff members are fun and quirky and some are more formal - which is somewhat different from SeaDream, and Azamara. Of course, it depends on how the client interacts with the staff, too.
In the Caribbean, they do Caviar in the Surf, which is fun, at least for the first 10 minutes. You can eat as much Caviar and drink as much Champagne as you can on the beach. It happens usually around lunchtime. If you have an excursion that ends late, they may or may not wait for you. But they will serve you caviar when you ask anyway - one portion has say 200 eggs, two people's has 300, if you're in a group of 4... then 400 eggs - you get what I mean... unless they really really do like you. They never liked me enough.
They have water toys, which they bring out in certain areas with calm seas. The Caribbean is a prime spot. It's certainly fun.
I find their food a bit more sophisticated than both Oceania and Azamara. Whether one likes it, it's personal. Like Oceania's bread, I very much like Seabourn's bread sticks (they're addictive) and fries/onion rings. If they put their breadsticks next to caviar, certain people, like me, would go straight to the breadsticks. They really really like me when I ask for breadsticks.
If you fancy something off the menu. Give them enough time, usually a day in advance, and they will make it for you. If it is very simple, half a day. Cunard loves to advertise that Queens Grill (and Princess Grill to a certain extent) cooks anything their guests request. Pretty much every cruise line in that market segment does that, as long as the request is reasonable. I find Seabourn's menu very good to excellent - always can find something I like. They do cook well.
The same goes for wine. If you don't like what they are serving one night, just let them know, and they will find something that you would like, or at least like better.
Their itineraries used to be quite repetitive. But I find these days, they are better. As we are less and less interested in port-intensive itineraries, it really does not matter to us.
Ship-sponsored excursions are usually good... as far as bus tours go. Prices are about the same as other luxury lines. But for a while already, Silversea and Regent have included excursions (I personally do not like it that much, even though I do have a Regent cruise booked; I prefer Seabourn's non-inclusion), so it is getting harder to compare in this regard.
Even the cheapest cabin is of a good size and nice. Very comfortable. Minibar included. Delicious toiletries (Molton Brown if I remember correctly... I remember that the shampoo and bath gel sound more like dessert, with ginger, mandarin oranges, honey, ginseng, etc, than soap).
I bet many Seabourn cruisers are still reminiscing about the old Trio - Pride, Legend, and Spirit. I do to a certain extent too. I have found some new loves throughout the years... but I still would sail with Seabourn, Silversea, x, y, z,... and Azamara - they are all good in their own way.
Nothing is perfect. My motto is to try different things that come my way, experience the freedom of choice, and love every little good thing each trip gives me.
Safe travels everybody!