The Apple website says the new graphics chip on the 13" is up to 1.8x faster than the previous model. Integrated graphics aren't that bad, these days, it seems.
http://www.apple.com/macbookpro/performance.html
13-inch MacBook Pro Graphics Performance
Up to 1.8x faster than previous-generation 13-inch MacBook Pro
1.8x
Doom 3
1.6x
Call of Duty 4
1.5x
Unreal Tournament 2004
1.3x
Quake 4