The big claim from the Clinton campaign has been Hillary's experience qualifies her to be president while Obama has done nothing but talk. Wes Walls at Ketchup and Caviar has a great post outlining the accomplishments of both.
It is really worth a read and completely blows away the Clinton camps argument. Just one number to compare... in his first year as a Senator, Obama introduced 152 bills, most of them substantive, and co-sponsored 427 more. In 6 years as a senator, Hillary introduced 20 bills... and most of them were about things like naming courthouses.
Read the list and you'll quickly see that Obama has exactly the kind of experience we need.