On previous types (737, 747, A320) we used full thrust for take-off, derated (or 'flexed' in the case of the A320) by using the Assumed Temperature Method (ATM).
This results in a take-off thrust known as 'D-TO' with an associated assumed or 'flex' temperature. In broad terms, the longer the runway, the higher the temperature and the lower the thrust. Regulations limit the thrust reduction to a maximum of 25%.
The Boeings also had the ability to use a fixed de-rate of 10% or 20% which was useful on short contaminated runways where Vmcg might be limiting. These settings are known as TO1 and TO2.
The 787 is the first jet I have flown which routinely combines both techniques. We can take off with TO, D-TO, TO1, D-TO1, TO2 and D-TO2.
The combinations of ATM and fixed derates (D-TO1 and D-TO2) give a very low thrust setting for take-off which results in much cooler EGT and thus extends engine life as well as improving reliability and reducing the overall chance of an engine failure (fleet-wise).
As far as I know, the 787 is the only big jet which uses this technique which is why it appears to climb at a shallower angle than other jetliners.
As an interesting comparison, using reduced thrust, the target all-engines pitch attitude on a 737 or A320 on initial climb is about 16-18*. For a 747 it is about 15*. For a 787 it is about 10*.