I grew 4 plants last year, with minimal return - they are a late and slow variety. I attempted to overwinter them all but only one survived. It did pretty well this year, not a massive return but certainly worthwhile, maybe 30 fruit from a middling sized plant, 2 to 2 and a half inches long and an inch to an inch and a half across. And with the heat they possess I'll use far fewer of them than I would a milder variety - I'm still using four year old Scotch Bonnets from the freezer.
I'll certainly grow them again, they make a great alternative to the likes of Habanero.