They sure are nice to have (I got carnival set), but they offer nothing unique. The things they produce you can get from a lot of other sources.Not to go too far, but Winter Market and Carnival sets were arguably superior to anything we have seen since then - Fire Phoenix might be a sole exception.
The brown bear offers the possibility to vastly increased troop production. For that reason I think it's superior to the ones you mentioned. But thats what suits me, players not fighting that much might not be that impressed by it.