Cloud is a-freaking-dorable! I am a therapist and he has helped my little clients talk about their feelings. He is well loved by boys as well as girls. I imagine Cloud would be equally at home with play therapy or CBT, as well as other modalities, as he can be very useful in facilitating psychoed about feelings, feeling identification, labeling, communication, etc. Kids immediately gravitate towards him with his unusual but cute and cuddly looks, and start putting feelings in his pouch. I have Bug too, which, with his folding wings, is great to talk about anxiety and bravery, but kids tend to gravitate towards Cloud more, with his neutral looks, his rotating head, and happy/sad faces. If you work with kids and are trying to pick a Kimochi to try first, I would start with Cloud.
In terms of his "personality", his rotating head and story make him the more "moody one", whose mood can change in a heartbeat, but you can really customize that to the situation at hand. A well loved buddy, both by the young ones and myself. I can't wait to get all the other Kimochis and feeling sets! The only catch is one of my clients did write on a custom feeling, but I haven't tried washing it off yet so I don't know how reusable those are. However, the pen did make a mess when it was used.