Compared to the current Sandy Bridge architecture, the new processors have both faster clock speeds and lower power consumption. Overall it's a modest speed increase that's optimized for notebooks.
From an ArsTechnica.com piece today:
"The standard, mainstream desktop processors now dissipate only 77W, compared to Sandy Bridge's 95W. Low power parts dissipate either 65W (for "S" model numbers) or 45W (for "T" model numbers). Clock speeds range from 2.3 GHz/3.3 GHz turbo, for the 45W Core i5-3570T, to 3.5 GHz/3.9 GHz turbo, for the overclockable Core i7-3770K. The mobile parts come in at 35W, 45W, and, for the top-end Extreme-branded processor, 55W. The 35W processor, the i7-3612QM, runs at 2.1 GHz/3.1 GHz turbo; the 55W chip runs at 2.9 GHz/3.8 GHz turbo....
" Tech Report's benchmarks cover a wide range of scenarios—gaming, productivity, scientific computing—and paint a consistent picture time and time again: Ivy Bridge is a little bit faster than the four core Sandy Bridges, and it uses a lot less power than Sandy Bridges, but workloads that spawn multiple compute-bound threads are still faster on the six core/twelve thread Sandy Bridge-E processors.
"Bucking tick conventions, however, is the new GPU. Not only does HD 4000 contain 33 percent more cores than HD 3000, with 16 shader cores compared to 12; each shader core is also more powerful, with larger caches, more threads per core, and more execution resources per core. HD 4000 (and HD 2500
, which is half an HD 4000) also supports Direct3D 11.0, compared to HD 3000's Direct3D 10. The display drivers will initially support OpenGL 3 and OpenCL 1.1; future updates should increase this to OpenGL 4. A detailed examination of the new GPU architecture can be found at Real World Technologies.
The result of the work done to the GPU is that it's a lot faster than the old one. AnandTech's review examines HD 4000's performance in a wide range of games and a small number of computational tasks. The GPU isn't going to challenge high-end discrete cards any time soon, but it's a healthy improvement on its predecessor, typically between 20 and 50 percent faster.