From DXO Mark
The Canon EOS 70D has been put through the paces by the folks at DXO Mark.
The highest rated APS-C sensor from Canon. That sounds great, until you see that it only scored 2 points more than the previous 18mp sensor found in countless Canon cameras. There are improvements in color depth, dynamic range and ISO performance. The sensor also has the highest pixel density in the aps-c lineup, so high detail rendering should be improved.
As always, take DXO's test numbers with a grain of salt. My eye has disagreed with them in the past.