Obviously it's biased, but the Radare site has a comparison table with "IDAPro demo" (i.e. the older IDA Free, v5.0), maybe it will be updated soon: http://rada.re/r/cmp.html
IDA Pro is far more usable, particularly for heavy-duty long-term users. There is a bit of a learning curve, but IDA Pro has a really efficient interface. You get the beauty and readability and nice flowchart-like layout that can be done in a GUI, while the keyboard control has efficiency like a well-made DOS or mainframe program.
