Can't comment on AKR, but we stayed at Anse Chastenet a few years ago in April. Overall, we thought it was so-so.
The food was pretty good, not great, but better than the average Caribbean resort. Views from the upper rooms were very nice, although we found ourselves staying at the beach all day and not hiking back and forth to the room since it was quite hilly.
I found the lack of AC a little uncomfortable, but not too bad, but my wife was bothered more by it. The biggest disadvantage we found was without AC it was harder to control the bugs, and St. Lucia does have a lot of bugs. My wife freaked out a little when she figured out what that cute romantic netting hanging around the bed was really for. And that it was really needed.
The diving was good, with nice short boat rides and not too many divers on a boat. The best part was the reef right off their beach which offered some good shore dives and endless hours of snorkeling. Pretty good corals and small critters, but not extraordinary.
We also found the locals in St. Lucia to be a bit cool. They weren't hostile or anything, but in some islands they seem to welcome tourists and are much friendlier. We also found that there were always people on Anse Chastenet's beach trying to sell us something - we'd have to go all the way to the far end to be able to lay on the beach without being pestered every 15 minutes.
Perhaps the telltale sign for us was that we haven't been back, whereas there are a number of other places on other islands we've returned to a number of times.