I have straight thick hair that is about bra strap length with long layers. It's good hair, but can get heavy and flat without some coaxing into voluminosity. I usually go with either a sock bun after blow drying or a 1.5" curling iron. In either case, this conditioner (plus the shampoo of the same name) give my hair noticeably more volume than other combos that I've used, and without a lot of buildup. I only wash my hair about every 4 days or so, so buildup is inevitable, but no more than with anything else.
Also, it smells like LUSH rockstar, which is a total plus.