Selkirks have a curly coat but are more like a British Shorthair in build and temperament - stocky bodies and a laid back approach to life, quietly and gently playful without being too hectic.
I have a 3 year old Cornish Rex cross who despite being half moggy shows absolutely NO sign of calming down in the near future, just today he catastrophised the kitchen for reasons unknown! He can open cupboard doors and is highly intelligent (and thus easily bored) and will make his own entertainment if he feels like it - things he has done include hiding in the kitchen bin and leaping out when I go past (making a huge mess in the process), and posting toy mice into the slot in the VCR. He also keeps undoing a bolt on the end of a sofa bed which is a slightly worrying act of sabotage.
You can tell where he is by the sound of things crashing to the floor, and he doesn't stop for long, I swear he barely slept for the first 18 months of his life. He is a little bit calmer now, but that still makes him more of a livewire than 95% of other cats. My Oriental Shorthairs are sedate in comparison.
Personally I love a mischievous and chaotic personality to share my home with, but that is not for everyone - Selkirks are a much calmer option if you want a curly cat but don't want them to make your own hair curl! They come in both longhair and shorthair - personally I prefer the shorthair, their coat resembles a lamb, is low maintenance, and very soft to the touch.