My experience isn’t recent, from around the time of that thread you linked.
I did a world challenge expedition as a teenager, and it definitely wasn’t worth the money / time spent fundraising.
A key thing to check is group size - there was 17 in ours plus 3 adults. It was far too many people, the needs of quieter group members got ignored as the more dominant personalities picked the activities, food, and accommodation.
I also found the adults with us weren’t great. 2 were teachers from my 6th form, who were clearly there for a bit of a jolly. The leader sent by World Challenge had very poor leadership skills, and despite apparently lots of experience, it seemed no knowledge of how to lead a hiking expedition for a mixed ability group.
The charity project we were assigned also wasn’t a charity. We were told we were visiting a school, except it was the school holidays so there were no children. We were tasked with doing DIY and fixing / decorating the school. A complete waste of time given none of us had the skills to do a decent job. Plus the owner of the land the school was on charged us to camp there whilst we did the work. Clearly they were in it to get the money, not because our service was actually of any use to them.
Overall, I wouldn’t recommend world challenge, but would suggest travelling independently with a group of trusted friends.