Reports are that the GT3e (presumably the faster-clocked desktop version) will perform similarly to the Nvidia GT640. Depending on whether you're interested in desktop or mobile performance is the big question. Also, driver support can also factor in here if you're gaming. Intel is getting better at drivers, but AMD will probably remain better through this generation.
On the desktop, AMD is using a higher TDP than Intel which gives them more headroom for graphics power so AMDs desktop APUs are currently better than Intel.
I would expect AMD to keep this lead (although by a smaller margin than current IVB/Trinity) through the Haswell/Richland and Kaveri generations(due later this year
). Mobile performance
is where Haswell is really set to threaten AMD. Intel can currently cram in more performance-per-watt than AMD (mostly due to fab) so I wouldn't be surprised to see Haswell GT3e eclipse Richland. I/we don't know what Kaveri will bring yet.
Main: i5-3570K, ASRock Z77 Pro4-M, Asus GTX660 TOP, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Hand-Built Wood Case