My parent's went to a couple's resort in the Smoky Mountain's region of Tennessee on their honeymoon, which was over thirty years ago, and they are still talking about how nice it was to this day, so it must have been nice.
My brother and his wife went to a couple's resort in Cozumel, Mexico on their honeymoon. They have awesome pictures from their trip and they plan to go back for their ten year anniversary, in a few years.
I haven't heard any bad couples resort stories, so it seems like it would be a fun and well-spent trip. But as with anything, everyone should remember you get what you pay for.
I am sure occasionally people can get lucky and find a really great deal on a great couples' resort, but for the most part, if a place seems too good to be true by the price, it probably is.
The more you spend on a couples resort, the more chance you have of having a good time. When you pay more, you get more, usually. I would recommend going to the different couples resorts sites online and see their reviews, that can give you a lot better insight than from the company itself.