The GPU engine on board Trinity is based on AMD's previous-generation Northern Islands family of GPU cores. You can loosely think of these as Radeon HD 6400 class GPUs, though the company is re-branding them as integrated Radeon HD 7600 and 7500 family cores. The GPU has an improved hardware tesselator over the previous gen Llano APU. In addition, it's VLIW4 design offers balanced stream processor cluster wit each of the four SPUs offering equal capability and more simplified scheduling, versus the VLIW5 design used in older Radeon HD series GPUs, for example. For a mobile architecture, this seemed like a reasonable low-risk path for AMD with good performance.
As part of the GPU block, AMD has also incorporated an updated version of their HD Media Accelerator with enhanced UVD (Unified Video Decoder) and AVC (Accelerated Video Converter blocks). The UVD block offers hardware offload for Blu-ray 3D, MPEG-4/DivX, and Picture-in-Picture with dual HD streams. In addition, within the HD Media Accelerator engine, A series APUs also offer AMD Quick Stream video streaming technology for prioritizing video stream packet data for uninterrupted video streaming.
And of course many software ISVs will be offering optimized versions of their applications to take advantage AMD's A-series video acceleration and conversion technologies.
The other major design advancement is AMD's new Piledriver compute cores...