In my opinion, Keisler deserves confirmation on the merits. I also believe Senate Democrats should begin to consider how they would like Democratic judicial nominees to be treated in the future, and set an example. This would be a welcome step toward a de-escalation in judicial nomination fights -- a step the next President (whomever he or she is) might appreciate.
I express no opinion as to whether Judge Keisler should be confirmed on the merits. However, there is a significant flaw in the "set an example" point. It assumes that Republican treatment of a future Democrat's nominees will in any way be influenced by how Democrats behave now.
Even were I to believe that a gesture of good faith by Democrats regarding judicial confirmations would be met with future "de-escalation" by the GOP, there is no way Senate Democrats believe it. They have been alive over these past few years of Republican control, after all. I suspect they think that treating Bush's nominees with respect and deference will yield much the same results as adopting slash-and-burn tactics: either way, Senate Republicans will show no restraint or fairness towards a Democratic President's nominees.
Does this mean I think that Democrat's should just get their licks in while they can? Not necessarily. But it does mean that if, for any reason, they think that Keisler will be the type of judge they don't want on the D.C. Circuit, they might as well block and delay him. It won't change the future any--and to be blunt, it's the GOP who will need to make the first move of good faith if the poisonous atmosphere they've created is going to break.