Both have a 10.1 inch screen, run Tegra 2 processors, and have 16 GB of internal storage. But ASUS's decision to use an IPS LCD definitely makes them the clear winner in the display category. ASUS also has a longer battery life, at around 9.5 hours to Iconia's 8 hours.
I think I'm going to go with the the Eee Pad Transformer, but I'm not positive yet. Am I missing anything?