If approved by the Senate, she will be the first Supreme Court appointee since 1972 not to have prior experience as a Federal judge.
I'll post more information and updates as the process goes on - but in the meantime my generic advice is: Read SCOTUSBlog.
They know more about this stuff than almost anyone, and they do a good job keeping up to date. Here for instance is their detailed summary of Kagan's experience, positives and negatives, and the perception of her by fellow lawyers and jurists.
Kagan is uniformly regarded as extremely smart, having risen to two of the most prestigious positions in all of law: dean of Harvard Law School and Solicitor General.
In government and academia, she has shown a special capacity to bring together people with deeply held, conflicting views. On a closely divided Supreme Court, that is an especially important skill.
Conservatives who she has dealt with respectfully (for example, Charles Fried and former Solicitors General to Republican Presidents) will likely come forward to rebut the claim that she is an extreme liberal.
She would also be only the fourth woman named to the Court in history, and President Obama would have named two. At age 50, she may serve for a quarter century or more, which would likely make her the President’s longest lasting legacy.
As with John Roberts, her service in a previous presidential Administration exposed her to a number of decisionmakers, who have confidence in her approach to legal questions.
The fact that she lacks a significant paper trail means that there is little basis on which to launch attacks against her, and no risk of a bruising Senate fight, much less a filibuster.
And finally, one point is often overlooked: Kagan had some experience on Capitol Hill and significant experience in the Executive Branch, not only as an attorney in the White House counsel’s office, but also as an important official dealing with domestic affairs. She has thus worked in the process of governing and does not merely come from what has recently been criticized (unfairly, in my view) as the “judicial monastery.”